Regulating serotonin expression can be used to treat psychotic depression. Mifepristone, a glu-cocorticoid receptor antagonist, is an effective candidate for psychotic depression treatment. However, the underlying mechanism related to serotonintransporter expression is poorly un-derstood. In this study, we cloned the human brain serotonintransporter into Xenopus oocytes, to establish an in vitro expression system. Two-electrode voltage clamp recordings were used to detect serotonintransporter activity. Our results show that mifepristone attenuates serotonintransporter activity by directly inhibiting the serotonintransporter, and suggests that the se-rotonintransporter is a pharmacological target of mifepristone for the treatment of psychotic depression.

Full Text Available Knockout (KO mice that lack the dopamine transporter (SL6A3; DAT display increased locomotion that can be attenuated, under some circumstances, by administration of drugs that normally produce psychostimulant-like effects, such as amphetamine and methylphenidate. These results have led to suggestions that DAT KO mice may model features of attention deficit hyperactivity disorder (ADHD and that these drugs may act upon serotonin (5-HT systems to produce these unusual locomotor decreasing effects. Evidence from patterns of brain expression and initial pharmacologic studies led us to use genetic and pharmacologic approaches to examine the influence of altered 5-HT1B receptor activity on hyperactivity in DAT KO mice. Heterozygous 5-HT1B KO and pharmacologic 5-HT1B antagonism both attenuated locomotor hyperactivity in DAT KO mice. Furthermore, DAT KO mice with reduced, but not eliminated, 5-HT1B receptor expression regained cocaine-stimulated locomotion, which was absent in DAT KO mice with normal levels of 5-HT1B receptor expression. Further experiments demonstrated that the degree of habituation to the testing apparatus determined whether cocaine had no effect on locomotion in DAT KO or reduced locomotion, helping to resolve differences among prior reports. These findings of complementation of the locomotor effects of DAT KO by reducing 5-HT1B receptor activity underscore roles for interactions between specific 5-HT receptors and dopamine (DA systems in basal and cocaine-stimulated locomotion and support evaluation of 5-HT1B antagonists as potential, non-stimulant ADHD therapeutics.

Genetic association studies suggest that variations in the 5-hydroxytryptamine (5-HT; serotonin) transporter (5-HTT) gene are associated with susceptibility to psychiatric disorders such as anxiety or posttraumatic stress disorder. Individuals carrying high 5-HTT-expressing gene variants display low amygdala reactivity to fearful stimuli. Mice overexpressing the 5-HTT (5-HTTOE), an animal model of this human variation, show impaired fear, together with reduced fear-evoked theta oscillations in the basolateral amygdala (BLA). However, it is unclear how variation in 5-HTT gene expression impacts on the microcircuitry of the BLA to change behavior. We addressed this issue by investigating the activity of parvalbumin (PV)-expressing interneurons (PVINs), the biggest IN population in the basal amygdala (BA). We found that increased 5-HTT expression impairs the recruitment of PVINs (measured by their c-Fos immunoreactivity) during fear. Ex vivo patch-clamp recordings demonstrated that the depolarizing effect of 5-HT on PVINs was mediated by 5-HT2A receptor. In 5-HTTOE mice, 5-HT-evoked depolarization of PVINs and synaptic inhibition of principal cells, which provide the major output of the BA, were impaired. This deficit was because of reduced 5-HT2A function and not because of increased 5-HT uptake. Collectively, these findings provide novel cellular mechanisms that are likely to contribute to differences in emotional behaviors linked with genetic variations of the 5-HTT.

The serotonintransporter (SERT) has been associated to diverse functions and diseases, though seldom to memory. Therefore, we made an attempt to summarize and discuss the available publications implicating the involvement of the SERT in memory, amnesia and anti-amnesic effects. Evidence indicates that Alzheimer's disease and drugs of abuse like d-methamphetamine (METH) and (+/-)3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") have been associated to decrements in the SERT expression and memory deficits. Several reports have indicated that memory formation and amnesia affected the SERT expression. The SERT expression seems to be a reliable neural marker related to memory mechanisms, its alterations and potential treatment. The pharmacological, neural and molecular mechanisms associated to these changes are of great importance for investigation.

The aim of this study was to investigate the effects of a mixed dietary intervention on behavioral symptoms in serotonintransporter knockout (5-HTT/) rats modeling the human 5-HTT length polymorphic region short-allele. Twenty female 5-HTT/ and 19 wild-type (5-HTT/) rats were fed for 3 months on a

This chapter dicusses the most recent data on the serotonintransporter knock-out rat, a unique rat model that has been generated by target-selected N-ethyl-N-nitrosourea (ENU) driven mutagenesis. The knock-out rat is the result of a premature stopcodon in the serotonintransporter gene, and the abs

The serotonintransporter is implicated in the uptake of the vasoconstrictor serotonin from the circulation into the platelets, where 95% of all blood serotonin is stored and released in response to vascular injury. In vivo studies indicated that platelet-derived serotonin mediates liver regeneratio

The serotonintransporter is implicated in the uptake of the vasoconstrictor serotonin from the circulation into the platelets, where 95% of all blood serotonin is stored and released in response to vascular injury. In vivo studies indicated that platelet-derived serotonin mediates liver regeneratio

The serotonintransporter is implicated in the uptake of the vasoconstrictor serotonin from the circulation into the platelets, where 95% of all blood serotonin is stored and released in response to vascular injury. In vivo studies indicated that platelet-derived serotonin mediates liver regeneratio

, obsessive-compulsive disorder, and eating disorders. Few studies have shown changes in serotonintransporter activity in schizophrenia and attention deficit hyperactivity disorder. By showing the scarcity of data in these psychiatric disorders, we highlight the potential for further investigation......Over the past 20 years, psychotropics affecting the serotonergic system have been used extensively in the treatment of psychiatric disorders. Molecular imaging, in particular PET, has allowed for elucidation of the essential contribution of the serotonintransporter to the pathophysiology...... of various psychiatric disorders and their treatment. We review studies that use PET to measure cerebral serotonintransporter activity in psychiatric disorders, focusing on major depressive disorder and antidepressant treatment. We also discuss opportunities and limitations in the application...

While there is strong evidence from rodent and human studies that a reduction in serotonintransporter (5-HTT) function in early-life can increase the risk for several neuropsychiatric disorders in adulthood, the effects of reduced 5-HTT function on behavior across developmental stages are

The serotonintransporter (SERT) terminates serotonergic signaling and enables refilling of synaptic vesicles by mediating reuptake of serotonin (5-HT) released into the synaptic cleft. The molecular and cellular mechanisms controlling SERT activity and surface expression are not fully understood...

The serotonintransporter (SERT) belongs to a family of sodium-chloride-dependent transporters responsible for uptake of amino acids and biogenic amines from the extracellular space. SERT represents a major pharmacological target in the treatment of several clinical conditions, including depressi...

Significantly lower platelet serotonin level (PSL) in patients with primary Sjogren's syndrome (pSS) than in healthy controls has been reported in our prior studies. In the present report, we demonstrated effect of functional polymorphisms in the serotonintransporter gene (5-HTT) on PSL. We describe a group of 61 pSS patients and 100 healthy individuals subjects, who received PSL measurement in our prior study. All subjects were genotyped for the promoter 5-HTTLPR (L/S), rs25531 (A/G) and intronic 5-HTTVNTRin2 (l/s) polymorphisms. Overall, the presence of 5-HTTVNTRin2 ss genotype was associated with significantly lower PSL in pSS patients, not in healthy controls. Reduced PSL in pSS patients is in line with hypothesis of association between chronic immunoinflammation and 5-HT system dysregulation, identifying additional mechanisms such as altered 5-HT transport as potential genetic factor contributing to PSL depletion.

Disruption of the serotonin system has been implicated in anxiety and depression and a related genetic variation has been identified that may predispose individuals for these illnesses. The relationship of a functional variation of the serotonintransporter promoter gene (5-HTTLPR) on serotonintransporter binding using in vivo imaging techniques have yielded inconsistent findings when comparing variants for short (s) and long (l) alleles. However, a significant 5-HTTLPR effect on receptor bi...

Background: Anxiety-related traits have been attributed to sequence variability in the genes coding for serotonin transmission in the brain. Two alleles, termed long (L) and short (S) differing by 44 base pairs, are found in a polymorphism identified in the promoter region of serotonintransporter gene. The presence of the short allele and SS and LS genotypes is found to be associated with the reduced expression of this gene decreasing the uptake of serotonin in the brain leading to various anxiety-related traits. Recurrent aphthous stomatitis (RAS) is an oral mucosal disease with varied etiology including the presence of stress, anxiety, and genetic influences. The present study aimed to determine this serotonintransporter gene polymorphism in patients with RAS and compare it with normal individuals. Materials and Methods: This study included 20 subjects with various forms of RAS and 20 normal healthy age- and gender-matched individuals. Desquamated oral mucosal cells were collected for DNA extraction and subjected to polymerase chain reaction for studying insertion/deletion in the 5-HTT gene-linked polymorphic region. Cross tabulations followed by Chi-square tests were performed to compare the significance of findings, P < 0.05 was considered statistically significant. Results: The LS genotype was the most common genotype found in the subjects with aphthous stomatitis (60%) and controls (40%). The total percentage of LS and SS genotypes and the frequency of S allele were found to be higher in the subjects with aphthous stomatitis as compared to the control group although a statistically significant correlation could not be established, P = 0.144 and 0.371, respectively. Conclusion: Within the limitations of this study, occurrence of RAS was not found to be associated with polymorphic promoter region in serotonintransporter gene. PMID:27274339

Full Text Available Serotonintransporter clustering is an important feature for regulation of this transporter activity. We used immunocytochemistry to analyze alterations in serotonintransporter clustering in blood lymphocytes of reeler mice. Serotonintransporter immunolabelling is observed mostly as a patchy staining in lymphocytes membranes. Comparison of the number and size of serotonintransporter clusters in wild-type mice, heterozygous reeler mice, and homozygous reeler mice showed an increase in the number and size of clusters in heterozygous reeler mice, but only an increase in clusters size in homozygous reeler mice. Reelin is down-regulated in the brain of schizophrenia, autism, and mood disorders, and is also expressed in blood plasma. There is the possibility therefore that alterations in serotonintransporter clustering in blood lymphocytes associated with a decrease in reelin expression may be operative in some cardiovascular or immune system alterations showing comorbidity with these mental disorders.

The plasmalemmal serotonintransporter uses transmembrane gradients of Na{sup +}, Cl{sup {minus}} and K{sup +} to accumulate serotonin within blood platelets. Transport is competitively inhibited by the antidepressant imipramine. Like serotonintransport, imipramine binding requires Na{sup +}. Unlike serotonin, however, imipramine does not appear to be transported. To gain insight into the mechanism of serotonintransport the author have analyzed the influences of Na{sup +} and Cl{sup {minus}}, the two ions cotransported with serotonin, on both serotonintransport and the interaction of imipramine and other antidepressant drugs with the plasmalemmal serotonintransporter of human platelets. Additionally, the author have synthesized, purified and characterized the binding of 2-iodoimipramine to the serotonintransporter. Finally, the author have conducted a preliminary study of the inhibition of serotonintransport and imipramine binding produced by dicyclohexylcarbodiimide. My results reveal many instances of positive heterotropic cooperativity in ligand binding to the serotonintransporter. Na{sup +} binding enhances the transporters affinity for imipramine and several other antidepressant drugs, and also increases the affinity for Cl{sup {minus}}. Cl{sup {minus}} enhances the transporters affinity for imipramine, as well as for Na{sup +}. At concentrations in the range of its K{sub M} for transportserotonin is a competitive inhibitor of imipramine binding. At much higher concentrations, however, serotonin also inhibits imipramines dissociation rate constant. This latter effect which is Na{sup +}-independent and species specific, is apparently produced by serotonin binding at a second, low affinity site on, or near, the transporter complex. Iodoimipramine competitively inhibit both ({sup 3}H)imipramine binding and ({sup 3}H)serotonintransport.

A series of compounds in the 4-fluoroalkyl-3-halophenyl nortropanes and 4-haloethenylphenyl tropane families are described as diagnostic and therapeutic agents for diseases associated with serotonintransporter dysfunction. These compounds bind to serotonintransporter protein with high affinity and selectivity. The invention provides methods of synthesis which incorporate radioisotopic halogens at a last step which permit high radiochemical yield and maximum usable product life. The radiolabeled compounds of the invention are useful as imaging agents for visualizing the location and density of serotonintransporter by PET and SPECT imaging.

Introduction: Imaging of the serotonergic innervation of the brain using positron emission tomography (PET) with the serotonintransporter (SERT) ligand [{sup 11C}] (+)McN5652 might be affected by serotonin in the synaptic cleft if there is relevant interaction between [{sup 11}C] (+)McN5652 and serotonin at the SERT. The aim of the present study therefore was to pharmacologically characterize the interaction of [{sup 11}C] (+)McN5652 and serotonin at the SERT. Methods: In vitro saturation analyses of [{sup 3}H]serotonin uptake into HEK293 cells stably expressing the human SERT were performed in the absence and presence of unlabelled (+)McN5652. Data were evaluated assuming Michaelis-Menten kinetics. Results: Unlabelled (+)McN5652 significantly reduced the maximal rate of serotonintransport V {sub max} of SERT without affecting the Michaelis-Menten constant K {sub M}. Conclusions: This finding indicates that (+)McN5652 inhibits serotonintransport through the SERT in a noncompetitive manner. This might suggest that [{sup 11}C] (+)McN5652 PET is not significantly affected by endogenous serotonin.

Halogenated naphthyl methoxy piperidines having a strong affinity for the serotonintransporter are disclosed. Those compounds can be labeled with positron-emitting and/or gamma emitting halogen isotopes by a late step synthesis that maximizes the useable lifeterm of the label. The labeled compounds are useful for localizing serotonintransporter sites by positron emission tomography and/or single photon emission computed tomography.

The serotonergic and dopaminergic systems are involved in a wide range of emotional and behavioral aspects of animals and humans and are involved in many neuropsychiatric disorders. Selective serotonin (5-HT) reuptake inhibitors (SSRIs) are designed to block the 5-HT transporter (SERT), thereby increasing the available 5-HT in the brain. Functional imaging with specific SERT and dopamine transporter (DAT) ligands contributes to the study of the SSRI-transporter interaction. First, we evaluated the feasibility of a canine model in the study of the SERT and DAT with the radioligands [{sup 123}I]-{beta}-CIT and [{sup 123}I]-FP-CIT as well as single-photon emission computed tomography imaging. Second, we studied the effect of SSRIs (sertraline, citalopram and escitalopram) on the SERT and DAT in two dogs. The position of the canine model in the study of the SERT and DAT is discussed and compared with other animal models.

To establish a purification procedure for the human serotonintransporter (hSERT) we expressed in Sf9 insect cells an epitope-tagged version of the transporter containing a FLAG epitope at the N-terminus and a polyhistidine tail at the C-terminus (FLAG-hSERT-12H). For purification, the transporter...

Exercise raises brain serotonin release and is postulated to cause fatigue in athletes; ingestion of branched-chain amino acids (BCAA), by competitively inhibiting tryptophan transport into brain, lowers brain tryptophan uptake and serotonin synthesis and release in rats, and reputedly in humans prevents exercise-induced increases in serotonin and fatigue. This latter effect in humans is disputed. But BCAA also competitively inhibit tyrosine uptake into brain, and thus catecholamine synthesis and release. Since increasing brain catecholamines enhances physical performance, BCAA ingestion could lower catecholamines, reduce performance and thus negate any serotonin-linked benefit. We therefore examined in rats whether BCAA would reduce both brain tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis. Sedentary and exercising rats received BCAA or vehicle orally; tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis rates were measured 1 h later in brain. BCAA reduced brain tryptophan and tyrosine concentrations, and serotonin and catecholamine synthesis. These reductions in tyrosine concentrations and catecholamine synthesis, but not tryptophan or serotonin synthesis, could be prevented by co-administering tyrosine with BCAA. Complete essential amino acid mixtures, used to maintain or build muscle mass, were also studied, and produced different effects on brain tryptophan and tyrosine concentrations and serotonin and catecholamine synthesis. Since pharmacologically increasing brain catecholamine function improves physical performance, the finding that BCAA reduce catecholamine synthesis may explain why this treatment does not enhance physical performance in humans, despite reducingserotonin synthesis. If so, adding tyrosine to BCAA supplements might allow a positive action on performance to emerge.

A major problem with the selective serotonin reuptake inhibitors (SSRIs) is the delayed onset of action. A reason for that may be that the initial SSRI-induced increase in serotonin levels activates somatodendritic 5-HT(1A) autoreceptors, causing a decrease in serotonin release in major forebrain areas. It has been suggested that compounds combining inhibition of the serotonintransport protein with antagonistic effects on the 5-HT(1A) receptor will shorten the onset time. The anxiolytic drug buspirone is known as 5-HT(1A) partial agonist. In the present work, we are studying the inhibition of the serotonintransporter protein by a series of buspirone analogues by molecular modelling and by experimental affinity measurements. Models of the transporter protein were constructed using the crystal structure of the Escherichia coli major facilitator family transporter-LacY and the X-ray structure of the neurotransmitter symporter family (NSS) transporter-LeuT(Aa) as templates. The buspirone analogues were docked into both SERT models and the interactions with amino acids within the protein were analyzed. Two putative binding sites were identified on the LeuT(Aa) based model, one suggested to be a high-affinity site, and the other suggested to be a low-affinity binding site. Molecular dynamic simulations of the LacY based model in complex with ligands did not induce a helical architecture of the LacY based model into an arrangement more similar to that of the LeuT(Aa) based model.

Serotonergic neurotransmission is modulated by the membrane-embedded serotonintransporter (SERT). SERT mediates the reuptake of serotonin into the presynaptic neurons. Conformational changes in SERT occur upon binding of ions and substrate and are crucial for translocation of serotonin across...... that were sensitized to detect a more outward-facing conformation of SERT. We found a novel high affinity outward-facing conformational state of the human SERT induced by serotonin. The ionic requirements for this new conformational response to serotonin mirror the ionic requirements for translocation...

Serotonin (5-HT) uptake by the human serotonintransporter (hSERT) is driven by ion gradients. The stoichiometry of transported 5-HT and ions is predicted to result in electroneutral charge movement. However, hSERT mediates a current when challenged with 5-HT. This discrepancy can be accounted for by an uncoupled ion flux. Here, we investigated the mechanistic basis of the uncoupled currents and its relation to the conformational cycle of hSERT. Our observations support the conclusion that the conducting state underlying the uncoupled ion flux is in equilibrium with an inward facing state of the transporter with K+ bound. We identified conditions associated with accumulation of the transporter in inward facing conformations. Manipulations that increased the abundance of inward facing states resulted in enhanced steady-state currents. We present a comprehensive kinetic model of the transport cycle, which recapitulates salient features of the recorded currents. This study provides a framework for exploring transporter-associated currents.

A well-known example for gene x environment interactions in psychiatry is the one involving the low activity (s) allelic variant of the serotonintransporter (5-HTT) promoter polymorphism (5-HTTLPR) that in the context of stress increases risk for depression. In analogy, 5-HTT knockout rodents are

A well-known example for gene x environment interactions in psychiatry is the one involving the low activity (s) allelic variant of the serotonintransporter (5-HTT) promoter polymorphism (5-HTTLPR) that in the context of stress increases risk for depression. In analogy, 5-HTT knockout rodents are h

AIM: To investigate the effect of serotonintransporter (5-HTT)inhibitor fluoxetine and antisense oligodeoxynucleotide (ODN)to extracelluar signal-regulated kinases (ERKs) on pulmonary arterial smooth muscle cells (PASMCs) proliferation induced by 5-HT. METHODS: Liposomal transfection was used to introduce ODNs to ERK1/2 into cultured rat PASMCs and the transfection efficiency was measured by observing the uptake of the

Affective startle probe methodology was used to examine the effects of nicotine administration and deprivation on emotional processes among individuals carrying at least one s allele versus those with the l/l genotype of the 5-Hydroxytryptamine (Serotonin) Transporter Linked Polymorphic Region, 5-HTTLPR in the promoter region of the serotonintransporter gene [solute ligand carrier family 6 member A4 (SLC6A4) or SERT]. Smokers (n=84) completed four laboratory sessions crossing deprivation (12-h deprived vs. non-deprived) with nicotine spray (nicotine vs. placebo). Participants viewed affective pictures (positive, negative, neutral) while acoustic startle probes were administered. We found that smokers with the l/l genotype showed significantly greater suppression of the startle response when provided with nicotine vs. placebo than those with the s/s or s/l genotypes. The results suggest that l/l smokers, who may have higher levels of the serotonintransporter and more rapid synaptic serotonin clearance, experience substantial reduction in activation of the defensive system when exposed to nicotine.

Tracking serotonergic pathways in the brain through immunodetection of serotonin has widely been used for the anatomical characterization of the serotonergic system. Immunostaining for serotonin is also frequently applied for the visualization of individual serotonin containing fibers and quantif......Tracking serotonergic pathways in the brain through immunodetection of serotonin has widely been used for the anatomical characterization of the serotonergic system. Immunostaining for serotonin is also frequently applied for the visualization of individual serotonin containing fibers...

The synthesis of serotonintransporter imaging agent [125I] -2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine([125I] ADAM) was reported. The chemical structure of the labeling precursor 5- (tributylstannyl) -2-((2-((dimethylamino)methyl)phenyl)thio)phenylamine and all its intermediates were verified by IR,1HNMR and MS. The .radioiodinated compound was prepared using iododestannylation reaction by hydrogen peroxide. Final radiochemical purity was above 95% determined by TLC.

Hepatic transporters and drug metabolizing enzymes (DMEs) play important roles in the pharmacological effects and (or) side-effects of many drugs, and are regulated by several mediators, including neurotransmitters. This work aimed to investigate whether serum levels of 5-hydroxytryptamine (5-HT) affected the expression of hepatic transporters or DMEs. The expression of hepatic transporters was assessed using the Western-blot technique in a 2,4,6-trinitrobenzenesulfonic-acid-induced rat model of post-infectious irritable bowel syndrome (PI-IBS), in which serum levels of 5-HT were significantly elevated. To further clarify the underlying mechanism, the 5-HT precursor 5-hydroxytryptophan (5-HTP) and the 5-HT depleting agent parachlorophenylalanine (pCPA) were applied to adjust serum levels of 5-HT. Serum levels of 5-HT were measured using LC-MS/MS; the expression of hepatic transporters, DMEs, and nuclear receptors were examined by Western-blot technique. Our results showed that in PI-IBS rats the expression of multidrug resistance protein 2 (Mrp2) was significantly decreased, while colonic enterochromaffin cell density and serum levels of 5-HT were all significantly increased. Moreover, 5-HTP treatment significantly increased serum levels of 5-HT and decreased the expression of Mrp2 and glycoprotein P (P-gp), whereas treatment with pCPA markedly decreased serum levels of 5-HT and increased the expression of Mrp2 and P-gp. Our results indicated that serum 5-HT regulates the expression of Mrp2 and P-gp, and the underlying mechanism may be related to the altered expression of the nuclear receptor constitutive androstane receptor (CAR).

The role of the serotonin (5-HT) system in the neurobiology and treatment of panic disorder (PD) remains unproven. Previously we detected lower brain 5-HT transporter (SERT) availability in PD, but the findings were preliminary and mainly limited to female patients. The aim of this study was to assess non-displaceable brain SERT binding potential (BP (ND)) in male and female patients with PD. The SERT BP (ND) was measured in groups of patients with PD (five males and six females) and matched healthy control subjects (12 males and 12 females) using positron emission tomography (PET) and [¹¹C]MADAM tracer. SERT BP (ND) were significantly higher in 13 of 20 studied brain regions, including several cortical and raphe areas, but lower in the hippocampus in males with PD as compared with healthy males. No significant differences in SERT BP (ND) were observed between female patients and controls. The results suggest gender-dependent regional differences in brain SERT availability and converge with previous PET findings of reduced 5-HT(1A) receptor binding in similar brain areas in PD. Distinctive functioning of the 5-HT system in males and females may underlie certain gender-dependent differences in expressions of PD.

Serotonin (5-HT) uptake by the human serotonintransporter (hSERT) is driven by ion gradients. The stoichiometry of transported 5-HT and ions is predicted to result in electroneutral charge movement. However, hSERT mediates a current when challenged with 5-HT. This discrepancy can be accounted for by an uncoupled ion flux. Here, we investigated the mechanistic basis of the uncoupled currents and its relation to the conformational cycle of hSERT. Our observations support the conclusion that the conducting state underlying the uncoupled ion flux is in equilibrium with an inward facing state of the transporter with K+ bound. We identified conditions associated with accumulation of the transporter in inward facing conformations. Manipulations that increased the abundance of inward facing states resulted in enhanced steady-state currents. We present a comprehensive kinetic model of the transport cycle, which recapitulates salient features of the recorded currents. This study provides a framework for exploring transporter-associated currents. PMID:22072712

Introduction: The primary approach in assessing the status of brain serotonin neurons in human conditions such as major depression and exposure to the illicit drug ecstasy has been the use of neuroimaging procedures involving radiotracers that bind to the serotonintransporter (SERT). However, there has been no consistency in the selection of a 'SERT-free' reference region for the estimation of free and nonspecific binding, as occipital cortex, cerebellum and white matter have all been employed. Objective and Methods: To identify areas of human brain that might have very low SERT levels, we measured, by a semiquantitative Western blotting procedure, SERT protein immunoreactivity throughout the postmortem brain of seven normal adult subjects. Results: Serotonintransporter could be quantitated in all examined brain areas. However, the SERT concentration in cerebellar cortex and white matter were only at trace values, being approximately 20% of average cerebral cortex and 5% of average striatum values. Conclusion: Although none of the examined brain areas are completely free of SERT, human cerebellar cortex has low SERT binding as compared to other examined brain regions, with the exception of white matter. Since the cerebellar cortical SERT binding is not zero, this region will not be a suitable reference region for SERT radioligands with very low free and nonspecific binding. For SERT radioligands with reasonably high free and nonspecific binding, the cerebellar cortex should be a useful reference region, provided other necessary radioligand assumptions are met.

Reasoning often occurs under emotionally charged, opinion-laden circumstances. The belief-bias effect indexes the extent to which reasoning is based upon beliefs rather than logical structure. We examined whether emotional content increases this effect, particularly for adults genetically predisposed to be more emotionally reactive. SS/SLG carriers of the serotonintransporter genotype (5-HTTLPR) were less accurate selectively for evaluating emotional relational reasoning problems with belief-logic conflict relative to LALA carriers. Trait anxiety was positively associated with emotional belief-bias, and the 5-HTTLPR genotype significantly accounted for the variance in this association. Thus, deductive reasoning, a higher cognitive ability, is sensitive to differences in emotionality rooted in serotonin neurotransmitter function. PMID:22275169

Reasoning often occurs under emotionally charged, opinion-laden circumstances. The belief-bias effect indexes the extent to which reasoning is based upon beliefs rather than logical structure. We examined whether emotional content increases this effect, particularly for adults genetically predisposed to be more emotionally reactive. SS/SL(G) carriers of the serotonintransporter genotype (5-HTTLPR) were less accurate selectively for evaluating emotional relational reasoning problems with belief-logic conflict relative to L(A)L(A) carriers. Trait anxiety was positively associated with emotional belief-bias, and the 5-HTTLPR genotype significantly accounted for the variance in this association. Thus, deductive reasoning, a higher cognitive ability, is sensitive to differences in emotionality rooted in serotonin neurotransmitter function.

Despite consistent evidence that serotonin functioning affects stress reactivity and vulnerability to aggression, research on serotonin gene-stress interactions (G x E) in the development of aggression remains limited. The present study investigated variation in the promoter region of the serotonintransporter gene (5-HTTLPR) as a moderator of the…

Full Text Available BACKGROUND: Mucociliary clearance in the airways is driven by the coordinated beating of ciliated cells. Classical neuromediators such as noradrenalin and acetylcholine increase ciliary beat frequency and thus cilia-driven transport. Despite the fact that the neuromediator serotonin is ciliostimulatory in invertebrates and has been implied in releasing acetylcholine from the airway epithelium, its role in regulating cilia function in vertebrate airways is not established. METHODOLOGY/PRINCIPAL FINDINGS: We examined the effects of serotonin on ciliary beat frequency and cilia-driven particle transport in the acutely excised submerged mouse trachea and determined the sources of serotonin in this tissue by immunohistochemistry. Serotonin (100 microM increased cilary beat frequency (8.9+/-1.2 Hz to 17.0+/-2.7 Hz and particle transport speed (38.9+/-4.6 microm/s to 83.4+/-8.3 microm/s to an extent that was comparable to a supramaximal dose of ATP. The increase in particle transport speed was totally prevented by methysergide (100 microM. Blockade of muscarinic receptors by atropine (1 microM did not reduce the effect of serotonin, although it was effective in preventing the increase in particle transport speed mediated by muscarine (100 microM. Immunohistochemistry demonstrated serotonin in mast cells pointing towards mast cells and platelets as possible endogenous sources of serotonin. CONCLUSIONS/SIGNIFICANCE: These results indicate that serotonin is a likely endogenous mediator that can increase cilia-driven transport independent from acetylcholine during activation of mast cells and platelets.

Background Mucociliary clearance in the airways is driven by the coordinated beating of ciliated cells. Classical neuromediators such as noradrenalin and acetylcholine increase ciliary beat frequency and thus cilia-driven transport. Despite the fact that the neuromediator serotonin is ciliostimulatory in invertebrates and has been implied in releasing acetylcholine from the airway epithelium, its role in regulating cilia function in vertebrate airways is not established. Methodology/Principal Findings We examined the effects of serotonin on ciliary beat frequency and cilia-driven particle transport in the acutely excised submerged mouse trachea and determined the sources of serotonin in this tissue by immunohistochemistry. Serotonin (100 µM) increased cilary beat frequency (8.9±1.2 Hz to 17.0±2.7 Hz) and particle transport speed (38.9±4.6 µm/s to 83.4±8.3 µm/s) to an extent that was comparable to a supramaximal dose of ATP. The increase in particle transport speed was totally prevented by methysergide (100 µM). Blockade of muscarinic receptors by atropine (1 µM) did not reduce the effect of serotonin, although it was effective in preventing the increase in particle transport speed mediated by muscarine (100 µM). Immunohistochemistry demonstrated serotonin in mast cells pointing towards mast cells and platelets as possible endogenous sources of serotonin. Conclusions/Significance These results indicate that serotonin is a likely endogenous mediator that can increase cilia-driven transport independent from acetylcholine during activation of mast cells and platelets. PMID:19290057

controls with low seasonality scores and 17 patients diagnosed with seasonal affective disorder were scanned in both summer and winter to investigate differences in cerebral serotonintransporter binding across groups and across seasons. The two groups had similar cerebral serotonintransporter binding...... between summer and winter (Pbinding was positively associated with change in depressive symptom...... from the first longitudinal investigation of seasonal serotonintransporter fluctuations in both patients with seasonal affective disorder and in healthy individuals. Eighty 11 C-DASB positron emission tomography scans were conducted to quantify cerebral serotonintransporter binding; 23 healthy...

Selective serotonin reuptake inhibitors (SSRIs) modulate serotonergic neurotransmission by blocking reuptake of serotonin from the extracellular space. Up to now, it remains unclear how SSRIs achieve their antidepressant effect. However, task-based and resting state functional magnetic resonance imaging studies, have demonstrated connectivity changes between brain regions. Here, we use positron emission tomography (PET) to quantify SSRI’s main target, the serotonintransporter (SERT), and assess treatment-induced molecular changes in the interregional relation of SERT binding potential (BPND). Nineteen out-patients with major depressive disorder (MDD) and 19 healthy controls (HC) were included in this study. Patients underwent three PET measurements with the radioligand [11C]DASB: (1) at baseline, (2) after a first SSRI dose; and (3) following at least 3 weeks of daily intake. Controls were measured once with PET. Correlation analyses were restricted to brain regions repeatedly implicated in MDD pathophysiology. After 3 weeks of daily SSRI administration a significant increase in SERT BPND correlations of anterior cingulate cortex and insula with the amygdala, midbrain, hippocampus, pallidum and putamen (p < 0.05; false discovery rate, FDR corrected) was revealed. No significant differences were found when comparing MDD patients and HC at baseline. These findings are in line with the clinical observation that treatment response to SSRIs is often achieved only after a latency of several weeks. The elevated associations in interregional SERT associations may be more closely connected to clinical outcomes than regional SERT occupancy measures and could reflect a change in the regional interaction of serotonergic neurotransmission during antidepressant treatment. PMID:28220069

We examined a panel of 21 patients diagnosed with compulsive buying for two DNA sequence polymorphisms found in the gene that encodes the serotonintransport (5-HTT). One polymorphism, found in the promoter region of the 5-HTT gene, involves a 44-base pair (bp) deletion, and the other, found in the second intron, is due to variable numbers of a repeat sequence. We also typed a panel of 38 psychiatrically normal controls for both 5-HH markers. When compared to this control panel, no significant differences were seen for either 5-HTT marker among the compulsive buyers.

The human dopamine, norepinephrine, and serotonintransporters (hDAT, hNET, and hSERT) are carriers of neurotransmitters and targets for many drugs. Pioneering works in the past three years to elucidate experimental models of the Drosophila dDAT and human hSERT structures will rapidly impact the field of neuroscience. Here, we evaluated automated homology-based human models of these transporters, employing systematic physics-based, knowledge-based, and empirical-based check. Modeling guidelines were conveyed with attention to the central binding site (S1), secondary binding site (S2), and the extracellular loops EL2 and EL4. Application of new experimental models (dDAT and hSERT) will improve the accuracy of homology models, previously utilizing prokaryotic leucine transporter (LeuT) structure, and provide better predictions of ligand interactions, which is required for understanding of cellular mechanisms and for development of novel therapeutics.

Notwithstanding several neurotransmission systems are frequently related to memory formation; forgetting process and neurotransmission systems or their transporters; the role of γ-aminobutyric acid (GAT1), glutamate (EACC1), dopamine (DAT) and serotonin (SERT) is poorly understood. Hence, in this paper western-blot analysis was used to evaluate expression of GAT1, EAAC1, DAT and SERT during forgetting in trained and untrained rats treated with the selective serotonintransporter inhibitor fluoxetine, the amnesic drug d-methamphetamine (METH) and fluoxetine plus METH. Transporters expression was determined in the hippocampus (HIP), prefrontal cortex (PFC) and striatum (STR). Results indicated that forgetting of Pavlovian/instrumental autoshaping was associated to up-regulation of GAT1 (PFC and HIP) and DAT (PFC) while SERT (HIP) was down-regulated; no-changes were observed in striatum. Methamphetamine administration did not affect forgetting at 216 h post-training but up-regulated hippocampal DAT and EACC, prefrontal cortex DAT and striatal GAT1 or EACC1. Fluoxetine alone prevented forgetting, which was associated to striatal GAT1 and hippocampal DAT up-regulation, but prefrontal cortex GAT1 down-regulation. Fluoxetine plus METH administration was also able to prevent forgetting, which was associated to hippocampal DAT, prefrontal cortex SERT and striatal GAT1, DAT or SERT up-regulation, but prefrontal cortex GAT1 down-regulation. Together these data show that forgetting provokes primarily hippocampal and prefrontal cortex transporters changes; forgetting represent a behavioral process hardly modifiable and its prevention could causes different transporters expression patterns.

Full Text Available The competitive inhibitor cocaine and the non-competitive inhibitor ibogaine induce different conformational states of the human serotonintransporter. It has been shown from accessibility experiments that cocaine mainly induces an outward-facing conformation, while the non-competitive inhibitor ibogaine, and its active metabolite noribogaine, have been proposed to induce an inward-facing conformation of the human serotonintransporter similar to what has been observed for the endogenous substrate, serotonin. The ligand induced conformational changes within the human serotonintransporter caused by these three different types of ligands, substrate, non-competitive and competitive inhibitors, are studied from multiple atomistic molecular dynamics simulations initiated from a homology model of the human serotonintransporter. The results reveal that diverse conformations of the human serotonintransporter are captured from the molecular dynamics simulations depending on the type of the ligand bound. The inward-facing conformation of the human serotonintransporter is reached with noribogaine bound, and this state resembles a previously identified inward-facing conformation of the human serotonintransporter obtained from molecular dynamics simulation with bound substrate, but also a recently published inward-facing conformation of a bacterial homolog, the leucine transporter from Aquifex Aoelicus. The differences observed in ligand induced behavior are found to originate from different interaction patterns between the ligands and the protein. Such atomic-level understanding of how an inhibitor can dictate the conformational response of a transporter by ligand binding may be of great importance for future drug design.

The competitive inhibitor cocaine and the non-competitive inhibitor ibogaine induce different conformational states of the human serotonintransporter. It has been shown from accessibility experiments that cocaine mainly induces an outward-facing conformation, while the non-competitive inhibitor ibogaine, and its active metabolite noribogaine, have been proposed to induce an inward-facing conformation of the human serotonintransporter similar to what has been observed for the endogenous substrate, serotonin. The ligand induced conformational changes within the human serotonintransporter caused by these three different types of ligands, substrate, non-competitive and competitive inhibitors, are studied from multiple atomistic molecular dynamics simulations initiated from a homology model of the human serotonintransporter. The results reveal that diverse conformations of the human serotonintransporter are captured from the molecular dynamics simulations depending on the type of the ligand bound. The inward-facing conformation of the human serotonintransporter is reached with noribogaine bound, and this state resembles a previously identified inward-facing conformation of the human serotonintransporter obtained from molecular dynamics simulation with bound substrate, but also a recently published inward-facing conformation of a bacterial homolog, the leucine transporter from Aquifex Aoelicus. The differences observed in ligand induced behavior are found to originate from different interaction patterns between the ligands and the protein. Such atomic-level understanding of how an inhibitor can dictate the conformational response of a transporter by ligand binding may be of great importance for future drug design.

Chronic administration of selective serotonin reuptake inhibitors (SSRIs), which up-regulates central serotonin (5-HT) system function, enhances adult hippocampal neurogenesis. However, the relationship between central 5-HT system and adult neurogenesis has not fully been understood. Here, we report that lowering 5-HT level in adulthood is also able to enhance adult hippocampal neurogenesis. We used tamoxifen (TM)-induced Cre in Pet1-CreER(T2) mice to either deplete central serotonergic (5-HTergic) neurons or inactivate 5-HT synthesis in adulthood and explore the role of central 5-HT in adult hippocampal neurogenesis. A dramatic increase in hippocampal neurogenesis is present in these two central 5-HT-deficient mice and it is largely prevented by administration of agonist for 5-HTR2c receptor. In addition, the survival of new-born neurons in the hippocampus is enhanced. Furthermore, the adult 5-HT-deficient mice showed reduced depression-like behaviors but enhanced contextual fear memory. These findings demonstrate that lowering central 5-HT function in adulthood can also enhance adult hippocampal neurogenesis, thus revealing a new aspect of central 5-HT in regulating adult neurogenesis.

Rigorous data regarding fetal central nervous system (CNS) exposure after antidepressant exposure are sparse. The magnitude of serotonin reuptake inhibitor (SRI) CNS exposure was measured in three groups of rats using ex vivo autoradiography of the serotonintransporter (SERT): 1) in utero, 2) postnatal clearance after birth, and 3) exposure through lactation. Rats were exposed to one of five SRI-type antidepressants (escitalopram, fluoxetine, paroxetine, sertraline, and venlafaxine) administered continuously via osmotic minipumps to pregnant or nursing dams. Dam dosing was adjusted to reflect the 50th and 85th percentiles of serum concentrations observed in pregnant women. Embryonic day 21 rat pups exposed in utero exhibited >80% SERT occupancy in brain tissue, which is equivalent to that of the pregnant dam and similar to that reported for human pharmacotherapy. Venlafaxine was the exception with occupancies ranging from 61 to 92% across different litters. The magnitude of SERT occupancy is essentially equivalent between dams and fetuses. By postnatal day 4, high SERT occupancy was observed only in fluoxetine-exposed pups (41-92% occupancy). Significantly less, but measurable, exposure occurred via breast milk exposure even in the absence of detectable drug concentrations in nursing pup sera. Pups exposed to SRIs via breast milk for 3 or 7 days exhibited varying SERT occupancies (0-57% depending on the individual medication and dam dose). These data highlight the need for animal modeling of fetal and nursing infant drug exposure using clinically meaningful dosing strategies and appropriate CNS measures to develop rational treatment guidelines that systematically minimize fetal and neonatal medication exposure in humans.

Women and men differ in serotonin associated psychiatric conditions, such as depression, anxiety and suicide. Despite this, very few studies focus on sex differences in the serotonin system. Of the biomarkers in the serotonin system, serotonin(1A) (5-HT(1A)) receptor is implicated in depression, and anxiety and serotonintransporter (5-HTT) is a target for selective serotonin reuptake inhibitors, psychotropic drugs used in the treatment of these disorders. The objective of the present study was to study sex related differences in the 5-HT(1A) receptor and 5-HTT binding potentials (BP(ND)s) in healthy humans, in vivo. Positron emission tomography and selective radioligands [(11)C]WAY100635 and [(11)C]MADAM were used to evaluate binding potentials for 5-HT(1A) receptors (14 women and 14 men) and 5-HTT (8 women and 10 men). The binding potentials were estimated both on the level of anatomical regions and voxel wise, derived by the simplified reference tissue model and wavelet/Logan plot parametric image techniques respectively. Compared to men, women had significantly higher 5-HT(1A) receptor and lower 5-HTT binding potentials in a wide array of cortical and subcortical brain regions. In women, there was a positive correlation between 5-HT(1A) receptor and 5-HTT binding potentials for the region of hippocampus. Sex differences in 5-HT(1A) receptor and 5-HTT BP(ND) may reflect biological distinctions in the serotonin system contributing to sex differences in the prevalence of psychiatric disorders such as depression and anxiety. The result of the present study may help in understanding sex differences in drug treatment responses to drugs affecting the serotonin system.

Serotonintransporter (SERT) has been associated with drugs of abuse like d-methamphetamine (METH). METH is well known to produce effects on the monoamine systems but it is unclear how METH affects SERT and memory. Here the effects of METH and the serotonin reuptake inhibitor fluoxetine (FLX) on autoshaping and novel object recognition (NOR) were investigated. Notably, both memory tasks recruit different behavioral, neural and cognitive demand. In autoshaping task a dose-response curve for METH was determined. METH (1.0mg/kg) impaired short-term memory (STM; lasting less of 90min) in NOR and impaired both STM and long-term memory (LTM; lasting 24 and 48h) in autoshaping, indicating that METH had long-lasting effects in the latter task. A comparative autoradiography study of the relationship between the binding pattern of SERT in autoshaping new untrained vs. trained treated (METH, FLX, or both) animals was made. Considering that hemispheric dominance is important for LTM, hence right vs. left hemisphere of the brain was compared. Results showed that trained animals decreased cortical SERT binding relative to untrained ones. In untrained and trained treated animals with the amnesic dose (1.0mg/kg) of METH SERT binding in several areas including hippocampus and cortex decreased, more remarkably in the trained animals. In contrast, FLX improved memory, increased SERT binding, prevented the METH amnesic effect and re-established the SERT binding. In general, memory and amnesia seemed to make SERT more vulnerable to drugs effects.

Epidemiologic studies indicate that obsessive-compulsive disorder is genetically transmitted in some families, although no genetic abnormalities have been identified in individuals with this disorder. The selective response of obsessive-compulsive disorder to treatment with agents which block serotonin reuptake suggests the gene coding for the serotonintransporter as a candidate gene. The primary structure of the serotonin-transporter coding region was sequenced in 22 patients with obsessive-compulsive disorder, using direct PCR sequencing of cDNA synthesized from platelet serotonin-transporter mRNA. No variations in amino acid sequence were found among the obsessive-compulsive disorder patients or healthy controls. These results do not support a role for alteration in the primary structure of the coding region of the serotonin-transporter gene in the pathogenesis of obsessive-compulsive disorder. 27 refs.

For the first time, we implement a novel, single molecule approach to define the localization and mobility of the brain's major target of widely prescribed antidepressant medications, the serotonintransporter (SERT). SERT labeled with single quantum dot (Qdot) revealed unsuspected features of transporter mobility with cholesterol-enriched membrane microdomains (often referred to as ``lipid rafts'') and cytoskeleton network linked to transporter activation. We document two pools of surface SERT proteins defined by their lateral mobility, one that exhibits relatively free diffusion in the plasma membrane and a second that displays significantly restricted mobility and localizes to cholesterol-enriched microdomains. Diffusion model prediction and instantaneous velocity analysis indicated that stimuli that act through p38 MAPK-dependent signaling pathways to activate SERT trigger rapid SERT movements within membrane microdomains. Cytoskeleton disruption showed that SERT lateral mobility behaves a membrane raft-constrained, cytoskeleton-associated manner. Our results identify an unsuspected aspect of neurotransmitter transporter regulation that we propose reflects the dissociation of inhibitory, SERT-associated cytoskeletal anchors.

The factors that influence individual differences in decision making are not yet fully characterized, but convergent evidence is accumulating that implicates serotonin (5-HT) system function. Therefore, both genes and environments that influence serotonin function are good candidates for association with risky decision making. In the present study we examined associations between common polymorphisms in the serotonintransporter gene (SLC6A4; 5-HTTLPR and rs25531), the experience of childho...

Full Text Available Donatella Marazziti, Stefano Baroni, Irene Masala, Francesca Golia, Giorgio Consoli, Gabriele Massimetti, Michela Picchetti, Mario Catena Dell’Osso, Gino Giannaccini, Laura Betti, Antonio Lucacchini, Antonio CiapparelliDipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, University of Pisa, Pisa, ItalyAbstract: The present study explored the possible relationships between impulsivity, gender, and a peripheral serotonergic marker, the platelet serotonin (5-HT transporter (SERT, in a group of 32 healthy subjects. The impulsivity was measured by means of the Barratt Impulsivity Scale, version 11 (BIS-11, a widely used self-report questionnaire, and the platelet SERT was evaluated by means of the specific binding of 3H-paroxetine (3H-Par to platelet membranes, according to standardized protocols. The results showed that women had a higher BIS-11 total score than men, and also higher scores of two factors of the same scale: the motor impulsivity and the cognitive complexity. The analysis of the correlations revealed that the density of the SERT proteins, as measured by the maximum binding capacity (Bmax of 3H-Par, was significantly and positively related to the cognitive complexity factor, but only in men. Men showed also a significant and negative correlation with the dissociation constant, Kd, of (3H-Par binding, and the motor impulsivity factor. These findings suggest that women are generally more impulsive than men, but that the 5-HT system is more involved in the impulsivity of men than in that of women.Keywords: impulsivity, gender, serotonintransporter, Barratt Impulsivity Scale, platelets, 3H-paroxetine

RATIONALE: While individual differences in vulnerability to psychostimulants have been largely attributed to dopaminergic neurotransmission, the role of serotonin is not fully understood. OBJECTIVES: To study the rewarding and motivational properties of cocaine in the serotonintransporter knockout

RATIONALE: While individual differences in vulnerability to psychostimulants have been largely attributed to dopaminergic neurotransmission, the role of serotonin is not fully understood. OBJECTIVES: To study the rewarding and motivational properties of cocaine in the serotonintransporter knockout

Serotonergic neurotransmission is terminated by reuptake of extracellular serotonin (5-HT) by the high-affinity serotonintransporter (SERT). Selective 5-HT reuptake inhibitors (SSRIs) such as fluoxetine or escitalopram inhibit SERT and are currently the principal treatment for depression...

The serotonintransporter (SERT) regulates extracellular levels of the neurotransmitter serotonin (5-hydroxytryptamine) in the brain by facilitating uptake of released 5-hydroxytryptamine into neuronal cells. SERT is the target for widely used antidepressant drugs, including imipramine, fluoxetine...

Serotonin (5-HT) transporter (SERT) substrates like fenfluramine and 3,4-methylenedioxymethamphetamine cause long-term depletion of brain 5-HT, while certain other substrates do not. The 5-HT deficits produced by SERT substrates are dependent upon transporter proteins, but the exact mechanisms responsible are unclear. Here, we compared the pharmacology of several SERT substrates: fenfluramine, d-fenfluramine, 1-(m-chlorophenyl)piperazine (mCPP) and 1-(m-trifluoromethylphenyl)piperainze (TFMPP), to establish relationships between acute drug mechanisms and the propensity for long-term 5-HT depletions. In vivo microdialysis was carried out in rat nucleus accumbens to examine acute 5-HT release and long-term depletion in the same subjects. In vitro assays were performed to measure efflux of [(3)H]5-HT in rat brain synaptosomes and transporter-mediated ionic currents in SERT-expressing Xenopus oocytes. When administered repeatedly to rats (6 mg/kg, i.p., four doses), all drugs produce large sustained elevations in extracellular 5-HT (>5-fold) with minimal effects on dopamine. Importantly, 2 weeks after dosing, only rats exposed to fenfluramine and d-fenfluramine display depletion of brain 5-HT. All test drugs evoke fluoxetine-sensitive efflux of [(3)H]5-HT from synaptosomes, but d-fenfluramine and its bioactive metabolite d-norfenfluramine induce significantly greater SERT-mediated currents than phenylpiperazines. Our data confirm that drug-induced 5-HT release probably does not mediate 5-HT depletion. However, the magnitude of transporter-mediated inward current may be a critical factor in the cascade of events leading to 5-HT deficits. This hypothesis warrants further study, especially given the growing popularity of designer drugs that target SERT.

Growing evidence suggests serotonin's role in anxiety and depression is mediated by its effects on learned fear associations. Pharmacological and genetic manipulations of serotonin signaling in mice alter the retention of fear extinction learning, which is inversely associated with anxious temperament in mice and humans. Here, we test whether genetic variation in serotonin signaling in the form of a common human serotonintransporter polyadenylation polymorphism (STPP/rs3813034) is associated with spontaneous fear recovery after extinction. We show that the risk allele of this polymorphism is associated with impaired retention of fear extinction memory and heightened anxiety and depressive symptoms. These STPP associations in humans mirror the phenotypic effects of serotonintransporter knockout in mice, highlighting the STPP as a potential genetic locus underlying interindividual differences in serotonintransporter function in humans. Furthermore, we show that the serotonintransporter polyadenylation profile associated with the STPP risk allele is altered through the chronic administration of fluoxetine, a treatment that also facilitates retention of extinction learning. The propensity to form persistent fear associations due to poor extinction recall may be an intermediate phenotype mediating the effects of genetic variation in serotonergic function on anxiety and depression. The consistency and specificity of these data across species provide robust support for this hypothesis and suggest that the little-studied STPP may be an important risk factor for mood and anxiety disorders in humans.

Sertraline and fluoxetine are selective serotonin re-uptake inhibitors (SSRIs) that are widely prescribed to treat depression. They exert their effects by inhibiting the presynaptic plasma membrane serotonintransporter (SERT). All SSRIs possess halogen atoms at specific positions, which are key determinants for the drugs' specificity for SERT. For the SERT protein, however, the structural basis of its specificity for SSRIs is poorly understood. Here we report the crystal structures of LeuT, a bacterial SERT homolog, in complex with sertraline, R-fluoxetine or S-fluoxetine. The SSRI halogens all bind to exactly the same pocket within LeuT. Mutation at this halogen-binding pocket (HBP) in SERT markedly reduces the transporter's affinity for SSRIs but not for tricyclic antidepressants. Conversely, when the only nonconserved HBP residue in both norepinephrine and dopamine transporters is mutated into that found in SERT, their affinities for all the three SSRIs increase uniformly. Thus, the specificity of SERT for SSRIs is dependent largely on interaction of the drug halogens with the protein's HBP.

Sertraline and fluoxetine are selective serotonin re-uptake inhibitors (SSRIs) that are widely prescribed to treat depression. They exert their effects by inhibiting the presynaptic plasma membrane serotonintransporter (SERT). All SSRIs possess halogen atoms at specific positions, which are key determinants for the drugs' specificity for SERT. For the SERT protein, however, the structural basis of its specificity for SSRIs is poorly understood. Here we report the crystal structures of LeuT, a bacterial SERT homolog, in complex with sertraline, R-fluoxetine or S-fluoxetine. The SSRI halogens all bind to exactly the same pocket within LeuT. Mutation at this halogen-binding pocket (HBP) in SERT markedly reduces the transporter's affinity for SSRIs but not for tricyclic antidepressants. Conversely, when the only nonconserved HBP residue in both norepinephrine and dopamine transporters is mutated into that found in SERT, their affinities for all the three SSRIs increase uniformly. Thus, the specificity of SERT for SSRIs is dependent largely on interaction of the drug halogens with the protein's HBP.

Social anxiety disorder (SAD) is associated with increased fear-related neural activity in the amygdala and we recently found enhanced serotonin synthesis rate in the same region. Anxiolytic agents like selective serotonin re-uptake inhibitors (SSRIs) and neurokinin-1 receptor (NK1R) antagonists reduce amygdala activity and may attenuate serotonin formation according to animal studies. Here, we examined the effects of SSRI pharmacotherapy, NK1R antagonism, and placebo on serotonin synthesis rate in relation to neural activity, measured as regional cerebral blood flow (rCBF), and symptom improvement in SAD. Eighteen SAD patients were randomized to receive daily double-blind treatment for six weeks either with the SSRI citalopram (n=6; 40mg), the NK1R antagonist GR205171 (n=6; 5mg; 4 weeks following 2 weeks of placebo), or placebo (n=6). Serotonin synthesis rate at rest and rCBF during stressful public speaking were assessed, before and after treatment, using positron emission tomography with the tracers [(11)C]5-hydroxytryptophan and [(15)O]water respectively. The Liebowitz Social Anxiety Scale (LSAS-SR) indexed symptom severity. All groups exhibited attenuated amygdala serotonin synthesis rate after treatment, which was associated with reduced amygdala rCBF during public speaking and accompanied by symptom improvement. These results are consistent with the notion that serotonin in the amygdala exerts an anxiogenic influence and, conversely, that anxiolysis is achieved through decreased serotonin formation in the amygdala.

Background: Selective serotonin reuptake inhibitors (SSRIs) have been associated with an increased bleeding tendency. Objectives: To prospectively quantify the dose-response effects of paroxetine and the influence of the serotonintransporter gene (SLC6A4) promoter polymorphism (5-HTTLPR) on platele

.Objective: To assess the differential effects of MDMA and hallucinogen use on cerebral serotonintransporter (SERT) and serotonin(2A) receptor binding.Design: A positron emission tomography study of 24 young adult drug users and 21 nonusing control participants performed with carbon 11 (C-11)-labeled 3-amino-4-[2-[(di...

Larvae of Chironomus riparius respond to ion-poor and brackish water (IPW, BW) conditions by activating ion uptake mechanisms in the anal papillae and reducing ion absorption at the rectum, respectively. The role that the Malpighian tubules play in ion and osmoregulation under these conditions is not known in this species. This study examines rates of fluid secretion and major cation composition of secreted fluid from tubules of C. riparius reared in IPW, freshwater (FW) and BW. Fluid secretion of tubules from FW and BW larvae was similar but tubules from IPW larvae secrete fluid at higher rates, are more sensitive to serotonin stimulation, and the secreted fluid contains less Na(+) . Therefore in IPW, tubules work in concert with anal papillae to eliminate excess water while conserving Na(+) in the hemolymph. Tubules do not appear to play a significant role in ion/osmoregulation under BW. Serotonin immunoreactivity in the nervous system and gastrointestinal tract of larval C. riparius was similar to that seen in mosquito larvae with the exception that the hindgut was devoid of staining. Hemolymph serotonin titer was similar in FW and IPW; hence, serotonin is not responsible for the observed high rates of fluid secretion in IPW. Instead, it is suggested that serotonin may work in a synergistic manner with an unidentified hormonal factor in IPW. Ion transport mechanisms in the tubules of C. riparius are pharmacologically similar to those of other insects.

Clinical review of the present data on the effects of selective serotonin reuptake inhibitors (SSRIs) on male fertility was the objective of the study. PubMed and Scopus were searched for publications in English or Danish and reviewed. Human trials, animal studies and in vitro studies were included...

Modulation of the immune system by the CNS may involve serotonergic regulation via the brain serotonintransporters (SERT). This regulation may be disturbed in patients with CNS disorders including multiple sclerosis (MS). Central serotonergic mechanisms have not been investigated in MS by in vivo imaging. The objective of the study was to assess the availability of SERT in antidepressant-naive patients with MS by means of PET. Included in this study were 23 patients with MS and 22 matched healthy volunteers who were investigated with PET and the SERT-selective marker [{sup 11}C]DASB, and distribution volume ratios were determined. Clinical assessment of the patients included the expanded disability status scale, the MS fatigue scale Wuerzburger Erschoepfungsinventar bei MS (WEIMuS) and the Beck Depression Inventory (BDI). The PET data were analysed with both volume-of-interest and voxel-based analyses to determine regional SERT availability. Patients had lower SERT availability in the cingulate cortex, the thalamus and the insula, and increased availability in the orbitofrontal cortex. Patients with relapsing/remitting MS tended to have lower SERT in the hippocampus, whereas patients with primary progressive disease showed increased SERT availability in prefrontal regions. There was a positive correlation between SERT availability in the insula and both depression and fatigue scores (r = 0.56 vs. BDI, p = 0.02; r = 0.49 vs. WEIMuS, p = 0.05). Serotonergic neurotransmission in MS patients is altered in limbic and paralimbic regions as well as in the frontal cortex that this appears to contribute to psychiatric symptoms of MS. (orig.)

Pharmacological manipulation of serotonergic neurotransmission in healthy volunteers impacts on cognitive test performance. Specifically, markers of serotonin function are associated with attention and executive functioning, long-term memory, and general cognitive ability. The serotonintransporter...... (SERT) protein is a key regulator in the serotonin system. We hypothesized that higher performance on tests sensitive to serotonin would be associated with higher SERT levels in specific fronto-striatal brain regions....

The serotonintransporter (SERT) plays a critical role in regulating serotonin signaling by mediating reuptake of serotonin from the extracellular space. The molecular and cellular mechanisms controlling SERT levels in the membrane remain poorly understood. To study trafficking of surface resident....... Furthermore, internalized SERT co-localized with the lysosomal marker LysoTracker and not with transferrin. The sorting pattern was further confirmed by visualizing internalization of SERT using the fluorescent cocaine analogue JHC1-64, and by reversible and pulse chase biotinylation assays showing evidence...

Data suggest that the serotonin (5-hydroxytryptamine, 5-HT) system is implicated in the pathogenesis of multiple neuropsychiatric disorders and may also be involved in smoking behaviour since nicotine increases brain serotonin secretion. It is known that smoking behaviour is influenced by both genetic and environmental factors. The present review examines the role of the serotonintransporter gene (5-HTT) in smoking behaviour and investigating studies that showed association of 5-HTT gene with smoking. This study discusses a polymorphism which has been investigated by many researchers, as the bi-allelic insertion/deletion polymorphism in the 5′-flanking promoter region (5-HTTLPR). This gene has received considerable attention in attempts to understand the molecular determinants of smoking. Therefore, in the present study, the relationship between genetic polymorphism of serotonintransporter in smoking behaviour is reviewed considering the interactive effect of genetic factors.

Serotonintransporters (SERTs) are pre-synaptic proteins specialized for the clearance of serotonin following vesicular release at central nervous system (CNS) and enteric nervous system synapses. SERTs are high affinity targets in vivo for antidepressants such as serotonin selective reuptake inhibitors (SSRIs). These include 'medical' psychopharmacological agents such as analgesics and antihistamines, a plant extract called St John's Wort (Hypericum). Osteoclasts are the primary cells responsible for bone resorption. They arise by the differentiation of osteoclast precursors of the monocyte/macrophage lineage. The expression of SERTs was increased in RANKL-induced osteoclast-like cells. Using RANKL stimulation of RAW264.7 cells as a model system for osteoclast differentiation, we studied the direct effects of food factor on serotonin uptake. The SSRIs (fluoxetine and fluvoxamine) inhibited markedly (approximately 95%) in serotonintransport in differentiated osteoclast cells. The major components of St. John's Wort, hyperforin and hypericine were significantly decreased in serotonintransport activity. Thus, a new in vitro model using RANKL-induced osteoclast-like cells may be useful to analyze the regulation of SERT by food factors and SSRIs.

Serotonintransporters (SERTs) play an essential role in the termination and regulation of serotonin signaling in the brain. SERT is also the target of antidepressants and psychostimulants. Molecules with novel activities and modes of interaction with regard to SERT function are of great scientific and clinical interest. We explored structural regions outside the putative serotonin translocation pathway to identify potential binding sites for allosteric transporter modulators (ATMs). Mutational studies revealed a pocket of amino acids outside the orthosteric substrate binding sites located in the interface between extracellular loops 1 and 3 that when mutated affect transporter function. Using the structure of the bacterial transporter homolog leucine transporter as a template, we developed a structural model of SERT. We performed molecular dynamics simulations to further characterize the allosteric pocket that was identified by site-directed mutagenesis studies and employed this pocket in a virtual screen for small-molecule modulators of SERT function. In functional transport assays, we found that one of the identified molecules, ATM7, increased the reuptake of serotonin, possibly by facilitating the interaction of serotonin with transport-ready conformations of SERT when concentrations of serotonin were low and rate limiting. In addition, ATM7 potentiates 3,4-methylenedioxy-N-methylamphetamine (MDMA, "Ecstasy")-induced reversed transport by SERT. Taking advantage of a conformationally sensitive residue in transmembrane domain 6, we demonstrate that ATM7 mechanistically stabilizes an outward-facing conformation of SERT. Taken together these observations demonstrate that ATM7 acts through a novel mechanism that involves allosteric modulation of SERT function.

Full Text Available Serotonintransporters (SERTs are largely recognized for one aspect of their function—to transportserotonin back into the presynaptic terminal after its release. Another aspect of their function, however, may be to generate currents large enough to have physiological consequences. The standard model for electrogenic transport is the alternating access model, in which serotonin is transported with a fixed ratio of co-transported ions resulting in net charge per cycle. The alternating access model, however, cannot account for all the observed currents through SERT or other monoamine transporters. Furthermore, SERT agonists like ecstasy or antagonists like fluoxetine generate or suppress currents that the standard model cannot support. Here we survey evidence for a channel mode of transport in which transmitters and ions move through a pore. Available structures for dopamine and serotonintransporters, however, provide no evidence for a pore conformation, raising questions of whether the proposed channel mode actually exists or whether the structural data are perhaps missing a transient open state.

Objective To investigate the serotonin reuptake transporter (SERT) genetic polymorphisms in the 5 -hydroxytryptamine (5-HT) transporter gene-linked polymorphic region (5-HTTLPR) and the variable number tandem repeats (VNTRs) in intron 2 among Chinese people, and their relationship to the pathogenesis of irritable bowel syndrome (IBS);and to investigate the im-

The objectives of this thesis were to study cerebral serotonintransporters (SERT) in the diencephalon and striatal dopamine transporters (DAT) in humans in different metabolic conditions (i.e. lean, obese and insulin resistant state) in relation to feeding behavior and to investigate the early cons

in the VNTRs of all mammalian SERT genes. The number of these putative binding sites varies proportionally to the length of the VNTR. We propose that the intronic VNTR have been selectively targeted through mammalian evolution to finetune transcriptional regulation of the serotonin expression....

Ibogaine, a hallucinogenic alkaloid proposed as a treatment for opiate withdrawal, has been shown to inhibit serotonintransporter (SERT) noncompetitively, in contrast to all other known inhibitors, which are competitive with substrate. Ibogaine binding to SERT increases accessibility in the permeation pathway connecting the substrate-binding site with the cytoplasm. Because of the structural similarity between ibogaine and serotonin, it had been suggested that ibogaine binds to the substrate site of SERT. The results presented here show that ibogaine binds to a distinct site, accessible from the cell exterior, to inhibit both serotonintransport and serotonin-induced ionic currents. Ibogaine noncompetitively inhibited transport by both SERT and the homologous dopamine transporter (DAT). Ibogaine blocked substrate-induced currents also in DAT and increased accessibility of the DAT cytoplasmic permeation pathway. When present on the cell exterior, ibogaine inhibited SERT substrate-induced currents, but not when it was introduced into the cytoplasm through the patch electrode. Similar to noncompetitive transport inhibition, the current block was not reversed by increasing substrate concentration. The kinetics of inhibitor binding and dissociation, as determined by their effect on SERT currents, indicated that ibogaine does not inhibit by forming a long-lived complex with SERT, but rather binds directly to the transporter in an inward-open conformation. A kinetic model for transport describing the noncompetitive action of ibogaine and the competitive action of cocaine accounts well for the results of the present study.

Ibogaine, a hallucinogenic alkaloid proposed as a treatment for opiate withdrawal, has been shown to inhibit serotonintransporter (SERT) noncompetitively, in contrast to all other known inhibitors, which are competitive with substrate. Ibogaine binding to SERT increases accessibility in the permeation pathway connecting the substrate-binding site with the cytoplasm. Because of the structural similarity between ibogaine and serotonin, it had been suggested that ibogaine binds to the substrate site of SERT. The results presented here show that ibogaine binds to a distinct site, accessible from the cell exterior, to inhibit both serotonintransport and serotonin-induced ionic currents. Ibogaine noncompetitively inhibited transport by both SERT and the homologous dopamine transporter (DAT). Ibogaine blocked substrate-induced currents also in DAT and increased accessibility of the DAT cytoplasmic permeation pathway. When present on the cell exterior, ibogaine inhibited SERT substrate-induced currents, but not when it was introduced into the cytoplasm through the patch electrode. Similar to noncompetitive transport inhibition, the current block was not reversed by increasing substrate concentration. The kinetics of inhibitor binding and dissociation, as determined by their effect on SERT currents, indicated that ibogaine does not inhibit by forming a long-lived complex with SERT, but rather binds directly to the transporter in an inward-open conformation. A kinetic model for transport describing the noncompetitive action of ibogaine and the competitive action of cocaine accounts well for the results of the present study. PMID:22451652

We have characterized the interaction of the serotonintransporter ligand [{sup 3}H]-N,N-dimethyl-2-(2-amino-4-cyanophenylthio)-benzylamine (DASB) with rhesus monkey brain in vitro using tissue homogenate binding and autoradiographic mapping. [{sup 3}H]-DASB, a tritiated version of the widely used [{sup 11}C] positron emission tomography tracer, was found to selectively bind to a single population of sites with high affinity (K {sub d}=0.20{+-}0.04 nM). The serotonintransporter density (B {sub max}) obtained for rhesus frontal cortex was found to be 66{+-}8 fmol/mg protein using [{sup 3}H]-DASB, similar to the B {sub max} value obtained using the reference radioligand [{sup 3}H]-citalopram, a well-characterized and highly selective serotonin reuptake inhibitor (83{+-}22 fmol/mg protein). Specific binding sites of both [{sup 3}H]-DASB and [{sup 3}H]-citalopram were similarly and nonuniformly distributed throughout the rhesus central nervous system, in a pattern consistent with serotonintransporter localization reported for human brain. Regional serotonintransporter densities, estimated from optical densities of the autoradiographic images, were well correlated between the two radioligands. Finally, DASB and fluoxetine showed dose-dependent full inhibition of [{sup 3}H]-citalopram binding in a competition autoradiographic study, with K {sub i} values in close agreement with those obtained from rhesus brain homogenates. This side-by-side comparison of [{sup 3}H]-DASB and [{sup 3}H]-citalopram binding sites in rhesus tissue homogenates and in adjacent rhesus brain slices provides additional support for the use of [{sup 11}C]-DASB to assess the availability and distribution of serotonintransporters in nonhuman primates.

The aim of the present clinical positron emission tomography study was to examine if the 5-HTT is a common target, both for tricyclic antidepressants (TCAs) and selective serotonin reuptake inhibitors (SSRIs). Serotonintransporter (5-HTT) occupancy was estimated during treatment with TCA, SSRI and mirtazapine in 20 patients in remission from depression. The patients were recruited from out-patient units and deemed as responders to antidepressive treatment. The radioligand [¹¹C]MADAM was used to determine the 5-HTT binding potential. The mean 5-HTT occupancy was 67% (range 28-86%). There was no significant difference in 5-HTT occupancy between TCA (n=5) and SSRI (n=14). 5-HTT affinity correlated with the recommended clinical dose. Mirtazapine did not occupy the serotonintransporter. The results support that TCAs and SSRIs have a shared mechanism of action by inhibition of 5-HTT.

Full Text Available Abstract Background Several studies have hypothesized that genes regulating the components of the serotonin system, including serotonintransporter (5-HTTLPR and serotonin 1 B receptor (5-HT1B, may be associated with alcoholism, but their results are contradictory because of alcoholism’s heterogeneity. Therefore, we examined whether the 5-HTTLPR gene and 5-HT1B gene G861C polymorphism are susceptibility factors for a specific subtype of alcoholism, antisocial alcoholism in Han Chinese in Taiwan. Methods We recruited 273 Han Chinese male inmates with antisocial personality disorder (ASPD [antisocial alcoholism (AS-ALC group (n = 120 and antisocial non-alcoholism (AS-N-ALC group (n = 153] and 191 healthy male controls from the community. Genotyping was done using PCR-RFLP. Results There were no significant differences in the genotypic frequency of the 5-HT1B G861C polymorphism between the 3 groups. Although AS-ALC group members more frequently carried the 5-HTTLPR S/S, S/LG, and LG/LG genotypes than controls, the difference became non-significant after controlling for the covarying effects of age. However, the 5-HTTLPR S/S, S/LG, and LG/LG genotypes may have interacted with the 5-HT1B G861C C/C polymorphism and increased the risk of becoming antisocial alcoholism. Conclusion Our study suggests that neither the 5-HTTLPR gene nor the 5-HT1B G861C polymorphism alone is a risk factor for antisocial alcoholism in Taiwan’s Han Chinese population, but that the interaction between both genes may increase susceptibility to antisocial alcoholism.

Serotonin (5-HT) release and serotonin reuptake transporter (5-HTT) expression have been reported to be decreased in experimental colitis, in interleukin-10 knockout-associated colitis, and in patients with ulcerative colitis. Serotonin is known to play an important role in the pathogenesis of colitis, but individual genetic variants of 5-HTT gene in microscopic colitis and ulcerative colitis are not known. This study aimed to evaluate the association between the serotonintransporter gene promoter polymorphism (5-HTTLPR) and 5-HT concentration in microscopic colitis (MC) and ulcerative colitis (UC) patients. This prospective case-control study included 41 patients with microscopic colitis (age 19-82 years, mean 35 ± 13.6), 75 patients with ulcerative colitis (age 16-65 years, mean 38.5 ± 11.6), and 100 controls (age 20-64 years, mean 38 ± 11). 5-HTTLPR gene polymorphism was studied by polymerase chain reaction-based assay. 5-HT levels were measured by ELISA. The frequency of the 5-HTTLPR (SS) genotype was significantly lower in MC (12 %) patients compared to controls (30 %) (p microscopic colitis, suggesting that 5-HTTLPR is a potential candidate gene involved in the pathogenesis of microscopic colitis. Serotonin levels were significantly higher in microscopic colitis and ulcerative colitis patients compared to healthy controls.

extensively across the great apes and monkeys as well as in rodents while it is absent in non-mammals. As in humans, the VNTR sequence may be polymorphic within species and thus it may underlie both inter- and intraspecies differences. Also, we find new putative binding sites for several transcription factors...... in the VNTRs of all mammalian SERT genes. The number of these putative binding sites varies proportionally to the length of the VNTR. We propose that the intronic VNTR have been selectively targeted through mammalian evolution to finetune transcriptional regulation of the serotonin expression....

Full Text Available Prenatal exposure to serotonin reuptake inhibitor (SRI antidepressants and maternal depression may affect prefrontal cognitive skills (executive functions; EFs including self-control, working memory and cognitive flexibility. We examined long-term effects of prenatal SRI exposure on EFs to determine whether effects are moderated by maternal mood and/or genetic variations in SLC6A4 (a gene that codes for the serotonintransporter [5-HTT] central to the regulation of synaptic serotonin levels and behavior. Children who were exposed to SRIs prenatally (SRI-exposed N=26 and non-exposed (N=38 were studied at age 6 years (M=6.3 SD=0.5 using the Hearts & Flowers task (H&F to assess EFs. Maternal mood was measured during pregnancy (3rd trimester and when the child was age 6 years (Hamilton Depression Scale. Parent reports of child behavior were also obtained (MacArthur Health & Behavior Questionnaire. Parents of prenatally SRI-exposed children reported fewer child externalizing and inattentive (ADHD behaviors. Generalized estimate equation modeling showed a significant 3-way interaction between prenatal SRI exposure, SLC6A4 variant, and maternal mood at the 6-year time-point on H&F accuracy. For prenatally SRI-exposed children, regardless of maternal mood, the H&F accuracy of children with reduced 5HTT expression (a short [S] allele remained stable. Even with increasing maternal depressive symptoms (though all below clinical threshold, EFs of children with at least one short allele were comparable to children with the same genotype whose mothers reported few if any depressive symptoms – in this sense they showed resilience. Children with two long (L alleles were more sensitive to context. When their mothers had few depressive symptoms, LL children showed extremely good EF performance – better than any other group. When their mothers reported more depressive symptoms, LL children’s EF performance was worse than that of any other group.

We studied the correlation between response to fluvoxamine and serotonintransporter gene promoter region polymorphism (5-HTTLPR). Eighteen children with autistic disorder completed a 12-week double-blind, placebo-controlled, randomized crossover study of fluvoxamine. Behavioral assessments were obtained before and at 12 weeks of treatment.…

The serotonintransporter (SERT) plays a crucial role in anxiety. Accordingly, variance in SERT functioning appears to constitute an important pathway to individual differences in anxiety. The current study tested the hypothesis that genetic variation in SERT function is associated with variability

Background: Previous research highlights the significance of a functional polymorphism located in the promoter region (5-HTTLPR) of the serotonintransporter gene in emotional behaviour. This study examined the effect of the 5-HTTLPR polymorphism on emotion processing in a large number of healthy preschoolers. Methods: The 5-HTTLPR genotype was…

Novel rhodamine-labeled ligands, based on (S)-citalopram, were synthesized and evaluated for uptake inhibition at the human serotonin, dopamine, and norepinephrine transporters (hSERT, hDAT, and hNET, respectively) and for binding at SERT, in transiently transfected COS7 cells. Compound 14 demons...

The perception of pain is determined by a combination of genetic, neurobiological, cultural, and emotional factors. Recent studies have demonstrated an association between specific genotypes and pain perception. Particular focus has been given to the triallelic polymorphism in the promoter region of the serotonintransporter gene in relation to pain perception. The aim of this study was to investigate whether the modulatory effect of emotions mediated by visual stimuli on muscular pain perception is genotype dependent. A total of 150 healthy subjects were selected on the basis of their polymorphism in the serotonintransporter gene. First, visual conditioning was performed with positive, negative, and neutral pictures from the International Affective Picture System, and the unpleasantness/pleasantness of the pictures was rated. Second, visual conditioning stimuli were presented while experimental jaw muscle pain was evoked by injection of hypertonic saline into the masseter muscle, and participants continuously rated pain intensity on an electronic visual analogue scale. The pictures induced similar changes in emotions across the 3 genotype groups, and hypertonic saline evoked moderate pain levels in all participants. However, in participants with a high expression of the serotonintransporter protein, conditioning with negative pictures increased pain intensity and positive pictures decreased pain intensity when compared with neutral pictures. In contrast, there were no significant effects of the pictures on pain perception in participants with either intermediate or low expression of the protein. These results suggest that polymorphisms in the serotonintransporter gene play an important role in emotions modulation of muscle pain.

Environmental stimuli can influence behavior via the process of Pavlovian conditioning. Recent genetic research suggests that some individuals are more sensitive to environmental stimuli for behavioral guidance than others. One important mediator of this effect is serotonintransporter (5-HTT) genet

UNLABELLED: Serotonin-mediated mechanisms, in particular via the serotonintransporter (SERT), are thought to have an effect on food intake and play an important role in the pathophysiology of obesity. However, imaging studies that examined the correlation between body mass index (BMI) and SERT...... are sparse and provided contradictory results. The aim of this study was to further test the association between SERT and BMI in a large cohort of healthy subjects. METHODS: 127 subjects of the ENC DAT database (58 females, age 52 ± 18 years, range 20-83, BMI 25.2 ± 3.8 kg/m(2), range 18.2-41.1) were...

Context: Both hallucinogens and 3,4-methylenedioxy-methamphetamine( MDMA or "ecstasy") have direct agonistic effects on postsynaptic serotonin(2A) receptors, the key site for hallucinogenic actions. In addition, MDMA is a potent releaser and reuptake inhibitor of presynaptic serotonin.......Objective: To assess the differential effects of MDMA and hallucinogen use on cerebral serotonintransporter (SERT) and serotonin(2A) receptor binding.Design: A positron emission tomography study of 24 young adult drug users and 21 nonusing control participants performed with carbon 11 (C-11)-labeled 3-amino-4-[2-[(di......(methyl) amino) methyl] phenyl]sulfanylbenzonitrile (DASB) and fluorine 18 (F-18)-labeled altanserin, respectively. Scans were performed in the user group after a minimum drug abstinence period of 11 days, and the group was subdivided into hallucinogen-preferring users (n=10) and MDMA-preferring users (n=14...

The effect of administering the serotonin precursor 5-l-hydroxytryptophan, in conjunction with a monamine oxidase inhibitor phenelzine and a l-amino acid decarboxylase inhibitor carbidopa, on neurochemical changes in the concentrations of serotonin and 5-hydroxyindoleacetic acid (5-HIAA) in the cerebrospinal fluid of the cat were investigated. Results showed that this drug regimen led to increases of serotonin and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in the cerebrospinal fluid by 330 and 830 percent, respectively. Concomitantly, the threshold of ventricular fibrillation was found to be elevated by 42 percent and the effective refractory period was prolonged by 7 percent; the efferent sympathetic neural activity was suppressed in the normal heart. The results indicate that the enhancement of central serotoninergic neurotransmission can reduce the susceptibility of the heart to ventricular fibrillation mediated through a decline in sympathetic neural traffic to the heart.

Objectives: Some of the debilitating non-motor aspects of Parkinson’s disease (PD) are related to the serotonin system1. To investigate the involvement of the brain serotonergic system in a PD animal model, we measured the in vivo binding of [11C]-DASB to the serotonintransporter (SERT......) as a marker of serotonergic neurons. In this study, we use the in vivo capabilities of PET imaging to study serotonin neurotransmission in a minipig model of PD induced by the intracerebroventricular injection of lactacystin, an inhibitor of the ubiquitin proteasome system. Methods: Five female Göttingen......]-3-amino-4-(2-dimethylaminomethyl-phenylsulfanyl)-benzonitrile (11C-DASB), a label of SERT availability. Four pigs then received eight weekly injections of lactacystin dissolved in sterile saline, and one pig received saline alone, directly into the CSF through the access port. They were scanned...

TLR2 is a microbiota recognition receptor that has been described to contribute to intestinal homeostasis and to ameliorate inflammatory intestinal injury. In this context, serotonin (5-HT) has shown to be an essential intestinal physiological neuromodulator that is also involved in intestinal inflammatory diseases. Since the interaction between TLR2 activation and the intestinal serotoninergic system remains non-investigated, our main aim was to analyze the effect of TLR2 on intestinal serotonintransporter (SERT) activity and expression and the intracellular pathways involved. Caco-2/TC7 cells were used to analyze SERT and TLR2 molecular expression and SERT activity by measuring 5-HT uptake. The results showed that apical TLR2 activation inhibits SERT activity in Caco-2/TC7 cells mainly by reducing SERT protein level either in the plasma membrane, after short-term TLR2 activation or in both the plasma membrane and cell lysate, after long-term activation. cAMP/PKA pathway appears to mediate short-term inhibitory effect of TLR2 on SERT; however, p38 MAPK pathway has been shown to be involved in both short- and long-term TLR2 effect. Reciprocally, 5-HT long-term treatment yielded TLR2 down regulation in Caco-2/TC7 cells. Finally, results from in vivo showed an augmented intestinal SERT expression in mice Tlr2-/-, thus confirming our inhibitory effect of TLR2 on intestinal SERT in vitro. The present work infers that TLR2 may act in intestinal pathophysiology, not only by its inherent innate immune role, but also by regulating the intestinal serotoninergic system. PMID:28033388

Escitalopram the S-enantiomer of the racemate citalopram, is clinically more effective than citalopram in the treatment of major depressive disorder. However, the precise mechanism by which escitalopram achieves superiority over citalopram is yet to be determined. It has been hypothesized that the therapeutically inactive R-enantiomer competes with the serotonin-enhancing S-enantiomer at a low-affinity allosteric site on serotonin reuptake transporters (SERTs), and reduces the effectiveness of the S-enantiomer at the primary, high-affinity serotonin-binding site. This study summarizes the results of two recent single-photon emission computerized tomography studies measuring SERT occupancy in citalopram-treated and escitalopram-treated healthy volunteers, after a single dose and multiple doses (i.e. under steady-state conditions). The single-dose study showed no attenuating effect of R-citalopram. After multiple dosing, however, SERT occupancy was significantly reduced in the presence of R-citalopram. Under steady-state conditions, R-enantiomer concentrations were greater than for the S-enantiomer because of slower clearance of R-citalopram. A pooled analysis suggests that build-up of the R-enantiomer after repeated citalopram dosing may lead to increased inhibition of S-enantiomer occupancy of SERT. This review adds to the growing body of evidence regarding differences in the dynamics of SERT occupancy, that is, molecular mechanisms underlying the often-observed superior clinical efficacy of escitalopram compared with citalopram in major depressive disorder.

The development of suitable radioligands for brain imaging of the serotonintransporter is of great importance for the study of depression and other affective disorders. The potent and selective serotonintransporter ligand, 5-iodo-6-nitro-2-piperazinylquinoline, has been labelled with iodine-123 and used as a radioligand for single photon emission computerized tomography. To evaluate the potential of the bromine-76-labelled analogue, 5-bromo-6-nitroquipazine, as a radioligand for positron emission tomography (PET), its brain distribution and binding characteristics were examined in rats. In vivo brain distribution and ex vivo autoradiography demonstrated that [{sup 76}Br]5-bromo-6-nitroquipazine enters the brain rapidly. The regional brain distribution of [{sup 76}Br]5-bromo-6-nitroquipazine was consistent with the known distribution of serotonintransporters in the midbrain, pons, thalamus, striatum, and neocortex. Specific binding was inhibited by the selective serotonin reuptake inhibitor citalopram. The peripheral metabolism in plasma was rapid, but more than 90% of the radioactivity in brain represented unchanged radioligand 2 h postinjection (p.i.). A preliminary PET study was also performed in a baboon. Following the intravenous injection of [{sup 76}Br]5-bromo-6-nitroquipazine in a baboon, there was a conspicuous accumulation of radioactivity in thalamus, striatum, and pons. The radioactivity in these brain regions was 1.5 times higher than in the cerebellum at 3 h and 2.5-4 times higher at 24 h. A rapid metabolism of the radioligand in plasma was observed (38% unchanged after 5 min). The results indicate that [{sup 76}Br]5-bromo-6-nitroquipazine has potential for PET imaging of the serotonintransporter.

Disturbances in central serotonin function have been implicated in impulsive and aggressive behavior. A deletion/insertion polymorphism within the 5-HT transporter promoter gene (5-HTTLPR) is thought to be associated with disturbed impulse control, anxiety, and depression. The serotonintransporter (5-HTT) is the primary action site for selective serotonin reuptake inhibitors (SSRIs). Several studies of major depression have shown that the l allele of 5-HTTLPR is associated with better SSRI antidepressant effects than the s allele. This study investigates the association between response of impulsivity to treatment with fluoxetine and 5-HTTLPR polymorphism in 49 personality disordered patients. Additionally, we studied TPH1, 5HT1B and 5HT2C receptor polymorphisms as predictors of response in this population. Results reveal that patients with the l/l genotype of 5-HTTLPR had a significantly better response to fluoxetine when compared to s allele carriers, as evaluated on the basis of total (PG) (-5806 G>T), HTR1B (G861C) and HTR2C (G68C) genotype groups. This is the first study assessing the association between these polymorphisms and anti-impulsive response to fluoxetine in personality disorder. As the s genotype is associated with a poorer selective serotonin reuptake inhibitors response in major depression, bulimia nervosa and borderline personality disorder, it could represent a common biological background for SSRI response.

BACKGROUND: Serotonin is associated with symptoms of the irritable bowel syndrome, its action is terminated by the serotonintransporter protein. AIM: To assess the association between a functional polymorphism in the gene encoding for activity of the serotonintransporter protein and the irritable

The present study had two goals: first, to give a detailed description of a reliable method for full kinetic analysis of serotonintransporter (5HTt) on the membrane of human platelets, and second, as a main issue, to report on physiological influences on kinetic characteristics of this transmembrane transport on a large population of healthy individuals. Full kinetic analyses of platelet serotonin uptake were performed on 334 blood donors of both sexes by the use of 14C-radioisotopic method, which was first optimized according to assumptions of enzyme kinetic analyses, with regard to platelet concentration, duration of uptake, concentration of substrate as well as important technical parameters (underpressure of filtration, blanks, incubating temperature, etc). Kinetic parameters of platelet serotonin uptake in the whole population were for V(max): 142 +/- 25.3 pmol 5HT/10(8) platelets/minute and for K(m): 0.404 +/- 0.089 microM 5HT. Besides the report on kinetic values of 5HT transporter protein, we have also described major physiological influences on the mentioned parameters, V(max), K(m) and their derivative, V(max)/K(m) (transporter efficiency): range and frequency distribution of normal values, intraindividual stability over time, lack of age influence, gender dependence and seasonal variations. The report on kinetic values and main physiological influences on platelet serotonintransport kinetics, obtained by the use of thoroughly reassessed methodology, and on by far the largest human population studied until now, offers a reliable frame of reference for pathophysiological studies of this parameter in various clinical fields.

Aim:To investigate the electrophysiological effect of fluoxetine on serotonintransporter.Methods:A heterologous expression system was used to introduce human serotonintransporter(hSERT)into Xenopus oocytes.A 2-electrode voltage clamp technique was used to study the pharmacological properties of fluoxetine.Results:hSERT-expressing oocytes were perfused with 10 μmol/L serotonin (5-HT)to induce hSERT-current.The 5-HT-induced hSERT currents were dose-dependently reversed by fluoxetine.The RC50(concentration that achieved a 50% reversal)was approximately 3.12 μmol/L.Fluoxetine took more time to combine with hSERT than 5-HT did,and it was also slow to dissociate from hSERRT. This long-lasting effect of fluoxetine affected normal 5-HT transport.Fluoxetine significantly prolonged the time constant for 5-HT-induced hSERT current.These results might be used to explain the long-lasting anti-anxiety effect of fluoxetine in clinical practice,because it increases the concentration of 5-HT in the synaptic cleft by its enduring suppression of the function of 5-HT transporters.Conclusion:Fluoxetine inhibits 5-HT reuptake by competing with 5-HT and changing the normal dynamics of hSERT.

Multiscale computational models can provide systemic evaluation and prediction of neuropharmacological drug effects. To date, little computational modeling work has been done to bridge from intracellular to neuronal circuit level. A complex model that describes the intracellular dynamics of the presynaptic terminal of a serotonergic neuron has been previously proposed. By systematically perturbing the model's components, we identify the slow and fast dynamical components of the model, and the reduced slow or fast mode of the model is computationally significantly more efficient with accuracy not deviating much from the original model. The reduced fast-mode model is particularly suitable for incorporating into neurobiologically realistic spiking neuronal models, and hence for large-scale realistic computational simulations. We also develop user-friendly software based on the reduced models to allow scientists to rapidly test and predict neuropharmacological drug effects at a systems level.

Disturbances in the serotonergic system have been recognized in autism. To investigate the association between serotonin and dopamine transporters and autism, we studied 15 children (14 males, one female; mean age 8y 8mo [SD 3y 10mo]) with autism and 10 non-autistic comparison children (five males, five females; mean age 9y 10mo [SD 2y 8mo]) using…

The serotonintransporter (SERT) controls the strength and duration of serotonergic neurotransmission by the high-affinity uptake of ser otonin (5-HT) from extracellular fluid. SERT is a key target for many psychotherapeutic and abused drugs, therefore understanding how SERT activity and expression are regulated is of fundamental importance. A growing literature suggests that SERT activity is under regulatory control of the 5-HT1B autoreceptor. The present studies made use of mice with a cons...

Platelet serotonin content in patients in the acute period of stroke is an important index of clinical changes during the post stroke period as well as a predictor of development of mental disorders. We studied the association between two polymorphisms (5-HTTLPR and Val66Met BDNF) and the platelet serotonin content in 47 patients with stroke. We also investigated the moderating effect of genetic variants on the association between platelet serotonin content and development of affective and anxiety disorders in stroke patients in the acute period of stroke. The interaction effect of two polymorphisms on levels of platelet serotonin was found. The lowest level was observed in patients with the diplotype LL*ValVal, the highest level--in the group of patients with the LL genotype and genotypes containing at least one copy of a Met allele. No moderating effect of genetic variants on the relationship between serotonin content and affective or anxiety disorder was found.

Depression is difficult to detect in cancer patients, though its determination offers an opportunity to relieve patients' suffering in palliative care. Selective serotonin reuptake inhibitors (SSRIs) are the treatment of choice for mood disorders, but they show a highly variable response. The short allelic variants "s/s" and "s/l" of the 5-HTTLPR polymorphism in the promoter region of the serotonintransporter gene has been consistently associated with a poorer response to SSRIs. The aim of this study has therefore been to examine depression, anxiety and mental adaptation to cancer in terminally ill and depressed cancer patients, in relation to treatment with sertraline and to the 5-HTTLPR genetic polymorphism. Eleven consecutive depressed patients with different forms of advanced cancer who were admitted to the Hospice of the Casa di Cura "Pineta del Carso" (Trieste, Italy) were treated with sertraline for two weeks and their response was determined and related to 5-HTTLPR. Sertraline significantly reduced the average depression and anxiety subscale scores of HADS, as well as the scores of the subscales of Mini-MAC. When the effects of sertraline were analyzed in relation to the 5-HTTLPR polymorphism, only patients with the "l/l" allelic variant had significantly lower scores of HADS anxiety, Mini-MAC hopelessness-helplessness and anxious preoccupation, and a higher score for the fighting spirit of Mini-MAC; the depression score was significantly reduced in patients with both allelic variants. These data indicate that sertraline is effective after two weeks of treatment in terminally ill cancer patients, acting not only on depression but also on anxiety and mental adaptation to cancer. Moreover, the effect of sertraline significantly depended on the genetic polymorphism of the serotonintransporter, being more pronounced in patients carrying the "l/l" genetic variant; these findings seem to encourage the examination of a larger sample of patients.

Full Text Available There is ample evidence that prenatal exposure to valproate (or valproic acid, VPA enhances the risk of developing Autism Spectrum Disorders (ASD. In line with this, a single injection of VPA induces a multitude of ASD-like symptoms in animals such as rats and mice. However, there is equally strong evidence that genetic factors contribute significantly to the risk of ASD and indeed, like most other psychiatric disorders, ASD is now generally thought to results from an interaction between genetic and environmental factors. Given that VPA significantly impacts on the serotonergic system, and serotonin has strong biochemical and genetic links to ASD, we aimed to investigate the interaction between genetic reduction in the serotonintransporter and prenatal valproate administration. More specifically, we exposed both wildtype (SERT+/+ rats and rats heterozygous for the serotonintransporter deletion (SERT+/- to a single injection of 400 mg/kg VPA at gestational day (GD 12. The offspring, in adulthood, was assessed in four different tests: Elevated Plus Maze and Novelty Suppressed Feeding as measures for anxiety and prepulse inhibition (PPI and latent inhibition as measures for cognition and information processing. The results show that prenatal VPA significantly increased anxiety in both paradigm, reduced PPI and reduced conditioning in the latent inhibition paradigm. However, we failed to find a significant gene – environment interaction. We propose that this may be related to the timing of the VPA injection and suggest that whereas GD12 might be optimal for affecting normal rat, rats with a genetically compromised serotonergic system may be more sensitive to VPA at earlier time points during gestation. Overall our data are the first to investigate gene * environmental interactions in a genetic rat model for ASD suggest that timing may be of crucial importance to the long-term outcome.

Full Text Available Serotonin is a ubiquitous chemical transmitter with particularly important roles in the gastrointestinal, cardiovascular and central nervous systems. Modulation of serotonergic signaling occurs, in part, by uptake of the transmitter by the serotonintransporter (SERT. In the brain, SERT is the target for numerous antidepressants including tricyclic antidepressants and selective serotonin reuptake inhibitors (SSRIs. Despite the importance of SERT in human physiology, biochemical, biophysical and high-resolution structural studies have been hampered due to the instability of SERT in detergent micelles. To identify a human SERT (hSERT construct suitable for detailed biochemical and structural studies, we developed an efficient thermostability screening protocol and rapidly screened 219 mutations for thermostabilization of hSERT in complex with the SSRI paroxetine. We discovered three mutations-Y110A, I291A and T439S -that, when combined into a single construct, deemed TS3, yielded a hSERT variant with an apparent melting temperature (Tm 19°C greater than that of the wild-type transporter, albeit with a loss of transport activity. Further investigation yielded a double mutant-I291A and T439S-defined as TS2, with a 12°C increase in Tm and retention of robust transport activity. Both TS2 and TS3 were more stable in short-chain detergents in comparison to the wild-type transporter. This thermostability screening protocol, as well as the specific hSERT variants, will prove useful in studies of other integral membrane receptors and transporters and in the investigation of structure and function relationships in hSERT.

Antidepressant drugs produce therapeutic actions and many of their side effects via blockade of the plasma membrane transporters for serotonin (SERT/SLC6A2), norepinephrine (NET/SLC6A1), and dopamine (DAT/SLC6A3). Many antidepressants block several of these transporters; some are more selective. Mouse gene knockouts of these transporters provide interesting models for possible effects of chronic antidepressant treatments. To examine the role of monoamine transporters in models of depression DAT, NET, and SERT knockout (KO) mice and wild-type littermates were studied in the forced swim test (FST), the tail suspension test, and for sucrose consumption. To dissociate general activity from potential antidepressant effects three types of behavior were assessed in the FST: immobility, climbing, and swimming. In confirmation of earlier reports, both DAT KO and NET KO mice exhibited less immobility than wild-type littermates whereas SERT KO mice did not. Effects of DAT deletion were not simply because of hyperactivity, as decreased immobility was observed in DAT+/- mice that were not hyperactive as well as in DAT-/- mice that displayed profound hyperactivity. Climbing was increased, whereas swimming was almost eliminated in DAT-/- mice, and a modest but similar effect was seen in NET KO mice, which showed a modest decrease in locomotor activity. Combined increases in climbing and decreases in immobility are characteristic of FST results in antidepressant animal models, whereas selective effects on swimming are associated with the effects of stimulant drugs. Therefore, an effect on climbing is thought to more specifically reflect antidepressant effects, as has been observed in several other proposed animal models of reduced depressive phenotypes. A similar profile was observed in the tail suspension test, where DAT, NET, and SERT knockouts were all found to reduce immobility, but much greater effects were observed in DAT KO mice. However, to further determine whether these

The serotonintransporter (SERT), which belongs to a family of sodium/chloride-dependent transporters, is the major pharmacological target in the treatment of several clinical disorders, including depression and anxiety. In the present study we show that the dissociation...... rate, of [3H]S-citalopram from human SERT, is retarded by the presence of serotonin, as well as by several antidepressants, when present in the dissociation buffer. Dissociation of [3H]S-citalopram from SERT is most potently inhibited by S-citalopram followed by R......-citalopram, sertraline, serotonin and paroxetine. EC50 values for S- and R-citalopram are 3.6 +/- 0.4 microm and 19.4 +/- 2.3 microm, respectively. Fluoxetine, venlafaxine and duloxetine have no significant effect on the dissociation of [3H]S-citalopram. Allosteric modulation of dissociation...

ADAM (2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine) is suggested as a promising serotonintransporter (SERT) imaging agent for central nervous system. In this paper, biodistribution studies in rats showed that the initial uptake of 131I-ADAM in the brain was high (1.087%ID at 2 min post-injection), and consistently displayed the highest binding (between 60～240 min post-injection) in hypothalamus, a region known with the highest density of SERT. The specific binding((T/CB)-l) of 131I-ADAM in hypothalamus were 2.94, 3.03 and 3.09 at 60, 120 and 240 min post-injection, respectively. The (T/CB)-1 was significantly blocked by pretreatment with paroxetine, which is known as a serotonin site reuptake inhibitor, while another nonselective competing drug (5HT2A antagonist) Ketanserin, showed no block effect. The rat brain autoradiography and analysis showed that there was a high 131I-ADAM uptake in hypothalamus, the ratio of hypothalamus/cerebellum was significantly reduced from 7.94±0.39to 1.30±0.56 by pretreatment with paroxetine at 60 min post-injection. Blood clearance kinetics was performed in rats,and the initial half-life of 13.79 min and late half-life of 357.14 min were obtained. The kinetic equation is:C=3.6147e-0.0725t + 1.0413e-0.0028t. The thyroid uptake was 0.009% ID and 1.421% ID at 2 min and 120 min post-injection, respectively, suggesting that in vivo deiodination may be the major route of metabolism. Toxicity trial showed that the dose per kilogram administered to mice was 1000 times greater than that to humans, assuming a weight of 50kg. These data suggest that 131I-ADAM may be useful for SPECT imaging of SERT binding sites in the brain.

The serotonin 2C receptor regulates food uptake, and its activity is regulated by alternative pre-mRNA splicing. Alternative exon skipping is predicted to generate a truncated receptor protein isoform, whose existence was confirmed with a new antiserum. The truncated receptor sequesters the full-length receptor in intracellular membranes. We developed an oligonucleotide that promotes exon inclusion, which increases the ratio of the full-length to truncated receptor protein. Decreasing the amount of truncated receptor results in the accumulation of full-length, constitutively active receptor at the cell surface. After injection into the third ventricle of mice, the oligonucleotide accumulates in the arcuate nucleus, where it changes alternative splicing of the serotonin 2C receptor and increases pro-opiomelanocortin expression. Oligonucleotide injection reduced food intake in both wild-type and ob/ob mice. Unexpectedly, the oligonucleotide crossed the blood-brain barrier and its systemic delivery reduced food intake in wild-type mice. The physiological effect of the oligonucleotide suggests that a truncated splice variant regulates the activity of the serotonin 2C receptor, indicating that therapies aimed to change pre-mRNA processing could be useful to treat hyperphagia, characteristic for disorders like Prader-Willi syndrome.

Recent functional magnetic resonance imaging (fMRI) studies have revealed links between genetic polymorphisms and cognitive and behavioural processes. Serotonin is a classical neurotransmitter of central nervous system, and it is connected to the control of appetite and satiety. In this study, the relationship between the functional variation in the serotonintransporter gene and the activity in the left posterior cingulate cortex (PCC), a brain area activated by visual food stimuli was explored. Thirty subjects underwent serial fMRI studies and provided DNA for genetic analyses. Subjects homozygous for the long allele exhibited greater left PCC activity in the comparison food > non-food compared with individuals heterozygous or homozygous for the short allele. The association between genotype and activation was linear, the subjects with two copies of the long allele variant having the strongest activation. These results demonstrate the possible genetically driven variation in the response of the left PCC to visual presentation of food in humans.

Full Text Available The ability to effectively respond to emotional information carried in the human voice plays a pivotal role for social interactions. We examined how genetic factors, especially the serotonintransporter genetic variation (5-HTTLPR, affect the neurodynamics of emotional voice processing in infants and adults by measuring event-related brain potentials (ERPs. The results revealed that infants distinguish between emotions during an early perceptual processing stage, whereas adults recognize and evaluate the meaning of emotions during later semantic processing stages. While infants do discriminate between emotions, only in adults was genetic variation associated with neurophysiological differences in how positive and negative emotions are processed in the brain. This suggests that genetic association with neurocognitive functions emerges during development, emphasizing the role that variation in serotonin plays in the maturation of brain systems involved in emotion recognition.

Rationale Synthetic hallucinogenic tryptamines, especially those originally described by Alexander Shulgin, continue to be abused in the United States. The range of subjective experiences produced by different tryptamines suggests that multiple neurochemical mechanisms are involved in their actions, in addition to the established role of agonist activity at serotonin-2A (5-HT2A) receptors. Objectives This study evaluated the interaction of a series of synthetic tryptamines with biogenic amine neurotransmitter transporters and with serotonin (5-HT) receptor subtypes implicated in psychedelic effects. Methods Neurotransmitter transporter activity was determined in rat brain synaptosomes. Receptor activity was determined using calcium mobilization and DiscoveRx PathHunter® assays in HEK293, Gα16-CHO, and CHOk1 cells transfected with human receptors. Results Twenty-one tryptamines were analyzed in transporter uptake and release assays, and 5-HT2A, serotonin 1A (5-HT1A), and 5-HT2A β-arrestin functional assays. Eight of the compounds were found to have 5-HT-releasing activity. Thirteen compounds were found to be 5-HT uptake inhibitors or were inactive. All tryptamines were 5-HT2A agonists with a range of potencies and efficacies, but only a few compounds were 5-HT1A agonists. Most tryptamines recruited β-arrestin through 5-HT2A activation. Conclusions All psychoactive tryptamines are 5-HT2A agonists, but 5-HT transporter (SERT) activity may contribute significantly to the pharmacology of certain compounds. The in vitro transporter data confirm structure-activity trends for releasers and uptake inhibitors whereby releasers tend to be structurally smaller compounds. Interestingly, two tertiary amines were found to be selective substrates at SERT, which dispels the notion that 5-HT-releasing activity is limited only to primary or secondary amines. PMID:24800892

Serotonergic neurotransmission is involved in the regulation of physiological functions such as mood, sleep, memory, and appetite. Within the serotonin transmitter system, both the postsynaptically located serotonin 2A (5-HT2A) receptor and the presynaptic serotonintransporter (SERT) are sensitive...

Despite the well-established role of the human serotonintransporter (hSERT) in the treatment of depression, the molecular details of antidepressant drug binding are still not fully understood. Here we utilize amber codon suppression in a membrane-bound transporter protein to encode photocrosslin......Despite the well-established role of the human serotonintransporter (hSERT) in the treatment of depression, the molecular details of antidepressant drug binding are still not fully understood. Here we utilize amber codon suppression in a membrane-bound transporter protein to encode...

The neurotransmitter serotonin underlies many of the brain's functions. Understanding serotonin neurochemistry is important for improving treatments for neuropsychiatric disorders such as depression...

Full Text Available BACKGROUND: Serotonin signaling influences social behavior in both human and nonhuman primates. In humans, variation upstream of the promoter region of the serotonintransporter gene (5-HTTLPR has recently been shown to influence both behavioral measures of social anxiety and amygdala response to social threats. Here we show that length polymorphisms in 5-HTTLPR predict social reward and punishment in rhesus macaques, a species in which 5-HTTLPR variation is analogous to that of humans. METHODOLOGY/PRINCIPAL FINDINGS: In contrast to monkeys with two copies of the long allele (L/L, monkeys with one copy of the short allele of this gene (S/L spent less time gazing at face than non-face images, less time looking in the eye region of faces, and had larger pupil diameters when gazing at photos of a high versus low status male macaques. Moreover, in a novel primed gambling task, presentation of photos of high status male macaques promoted risk-aversion in S/L monkeys but promoted risk-seeking in L/L monkeys. Finally, as measured by a "pay-per-view" task, S/L monkeys required juice payment to view photos of high status males, whereas L/L monkeys sacrificed fluid to see the same photos. CONCLUSIONS/SIGNIFICANCE: These data indicate that genetic variation in serotonin function contributes to social reward and punishment in rhesus macaques, and thus shapes social behavior in humans and rhesus macaques alike.

The neurotransmitter, serotonin, has been implicated in aggressive behavior. The serotonintransporter (5-HTT), which reuptakes serotonin into the nerve terminal, plays a critical role in the regulation of serotonergic function. Previous western reports have demonstrated that the low-activity short (S) allele of the 5-HTT gene-linked polymorphic-region (5-HTTLPR) polymorphism is associated with aggressive behavior and associated personality traits. In the present study, we investigated this 5-HTTLPR genetic polymorphism in a group of Chinese males who had been convicted for extremely violent crime (n = 135) and a normal control group (n = 111). The proportion of S-allele carriers was significantly higher in the criminal group than in the controls (p = 0.006). A significant association was not demonstrated for the relationship between the 5-HTTLPR polymorphism and antisocial personality disorder, substance abuse or alcohol abuse in the criminal group. Our findings demonstrate that carriage of the low-activity S allele is associated with extremely violent criminal behavior in Chinese males, and suggests that the 5-HTT may be implicated in the mechanisms underlying violent behaviors.

The basolateral and lateral amygdala nuclei complex (BLC) is implicated in a number of emotional responses including conditioned fear and social anxiety. Based on previous studies demonstrating that enhanced serotonin release in the BLC leads to increased anxiety and fear responses, we hypothesized that pharmacologically depleting serotonin in the BLC using 5,7-dihydroxytryptamine (5,7-DHT) injections would lead to diminished anxiety and disrupted fear conditioning. To test this hypothesis, 5,7-DHT(a serotonin-depleting agent) was bilaterally injected into the BLC. Desipramine (a norepinephrine reuptake inhibitor) was systemically administered to prevent non-selective effects on norepinephrine. After 5days, 5-7-DHT-treated rats showed increases in the duration of social interaction (SI) time, suggestive of reduced anxiety-like behavior. We then used a cue-induced fear conditioning protocol with shock as the unconditioned stimulus and tone as the conditioned stimulus for rats pretreated with bilateral 5,7-DHT, or vehicle, injections into the BLC. Compared to vehicle-treated rats, 5,7-DHT rats had reduced acquisition of fear during conditioning (measured by freezing time during tone), also had reduced fear retrieval/recall on subsequent testing days. Ex vivo analyses revealed that 5,7-DHT reduced local 5-HT concentrations in the BLC by ~40% without altering local norepinephrine or dopamine concentrations. These data provide additional support for 5-HT playing a critical role in modulating anxiety-like behavior and fear-associated memories through its actions within the BLC.

Rationale Negative mood states are characterized by both stress hormone dysregulation and serotonergic dysfunction, reflected by altered thalamic serotonintransporter (5-HTT) levels. However, so far, no study examined the individual association between cortisol response and cerebral in vivo 5-HTT levels in patients suffering from negative mood states. Objective The objective of this cross-sectional study was to assess the interrelation of cortisol response, thalamic 5-HTT levels, and anxiety in healthy subjects and two previously published samples of patients with unipolar major depression (UMD) and obsessive–compulsive disorder (OCD), controlling for age, gender, 5-HTT genotype, smoking, and seasonality. Methods Regional 5-HTT levels and cortisol response to dexamethasone-corticotropin (Dex-CRH) challenge were assessed in consecutive samples of medication-free patients suffering from UMD (N=10) and OCD (N=10), and 20 healthy volunteers. The intervention used was combined Dex-CRH test and [11C]DASB positron emission tomography. The main outcome measures were: 5-HTT binding potential (BPND) in a predefined thalamic ROI, cortisol response defined as the maximum cortisol increase in the combined Dex-CRH-test, and state of anxiety from the state-trait-anxiety inventory. Results Reduced thalamic 5-HTT BPND was associated with increased cortisol response (r=−0.35, p<0.05; in patients: r=−0.53, p<0.01) and with increased state anxiety (r=−0.46, p<0.01), surviving correction for age, gender, 5-HTT genotype, smoking, and seasonality (p<0.05). The 5-HTT genotype, on the contrary, was not significantly associated with cortisol response (p=0.19) or negative mood (p=0.23). Conclusion The association between stress hormone response, thalamic 5-HTT levels, and anxiety in patients suffering from negative mood states suggests an interaction between two major mechanisms implicated in negative mood states in humans. PMID:20585760

Recognition memory is defined as the ability to recognize a previously encountered stimulus and has been associated with spatially and temporally distinct event-related potentials (ERPs). Allelic variations of the serotonintransporter gene (SLC6A4) have recently been shown to impact memory performance. Common variants of the serotonintransporter-linked polymorphic region (5HTTLPR) of the SLC6A4 gene result in long (l) and short (s) allelic variants with carriers of the s allele having lowered transcriptional efficiency. Thus, the current study examines the effects polymorphisms of the SLC6A4 gene have on performance and ERP amplitudes commonly associated with recognition memory. Electroencephalogram (EEG), genetic, and behavioral data were collected from sixty participants as they performed an item and source memory recognition task. In both tasks, participants studied and encoded 200 words, which were then mixed with 200 new words during retrieval. Participants were monitored with EEG during the retrieval portion of each memory task. EEG electrodes were grouped into four ROIs, left anterior superior, right anterior superior, left posterior superior, and right posterior superior. ERP mean amplitudes during hits in the item and source memory task were compared to correctly recognizing new items (correct rejections). Results show that s-carriers have decreased mean hit amplitudes in both the right anterior superior ROI 1000-1500ms post stimulus during the source memory task and the left anterior superior ROI 300-500ms post stimulus during the item memory task. These results suggest that individual differences due to genetic variation of the serotonintransporter gene influences recognition memory.

To investigate the structural basis for genetic regulation of the human serotonintransporter gene, a 1.8 kb fragment upstream to the cap site was cloned and sequenced. The promoter possesses a polymorphic repeat region with 16 and 14 repeats, respectively. Both were cloned and characterized....... The promoter sequence revealed an internal 379 bp fragment not reported in previous publications. This novel fragment contains consensus sequences for several transcription factors including SpI and GATA. DNA from 48 unrelated individuals was PCR amplified, in this region, to test for allelic variations. All...

The purified serotonintransporter (SERT) was spread at the air/water interface and the effects both of its surface density and of the temperature on its interfacial behavior were studied. The recorded isotherms evidenced the existence of a stable monolayer undergoing a lengthy rearrangement. SERT/ligand interactions appeared to be dependent on the nature of the studied molecules. Whereas an unrelated drug (chlorcyclizine) did not bind to the spread SERT, it interacted with its specific ligands. Compared to heterocyclic drugs, for which binding appeared to be concentration-dependent, a 'two-site' mechanism was evidenced for pinoline and imipramine.

For the development of new ligands as potential imaging agents for the serotonintransporter (SERT), a series of diphenyl ether derivatives have been synthesized, characterized, and evaluated for their in vitro binding affinities to the SERT. Among the above compounds, 2-(2-((dimethylamino)methyl)-4-fluoro-phenoxy)-5-bromobenzenamine (15) and 2-(2-((dimethylamino)methyl)-4-fluorophenoxy)-5-iodobenzene respectively. They can be further labeled with carbon-11, fluorine-18, iodine-123 or bromine-76, and evaluated as useful imaging agents for the SERT. Moreover, the study of the structure-activity relationship (SAR) provides some useful information for the future design of new ligands.

Full Text Available BACKGROUND: Women are at great risk for mood and anxiety disorders during their childbearing years and may become pregnant while taking antidepressant drugs. In the treatment of depression and anxiety disorders, selective serotonin reuptake inhibitors (SSRIs are the most frequently prescribed drugs, while it is largely unknown whether this medication affects the development of the central nervous system of the fetus. The possible effects are the product of placental transfer efficiency, time of administration and dose of the respective SSRI. METHODOLOGY/PRINCIPAL FINDINGS: In order to attain this information we have setup a study in which these parameters were measured and the consequences in terms of physiology and behavior are mapped. The placental transfer of fluoxetine and fluvoxamine, two commonly used SSRIs, was similar between mouse and human, indicating that the fetal exposure of these SSRIs in mice is comparable with the human situation. Fluvoxamine displayed a relatively low placental transfer, while fluoxetine showed a relatively high placental transfer. Using clinical doses of fluoxetine the mortality of the offspring increased dramatically, whereas the mortality was unaffected after fluvoxamine exposure. The majority of the fluoxetine-exposed offspring died postnatally of severe heart failure caused by dilated cardiomyopathy. Molecular analysis of fluoxetine-exposed offspring showed long-term alterations in serotonintransporter levels in the raphe nucleus. Furthermore, prenatal fluoxetine exposure resulted in depressive- and anxiety-related behavior in adult mice. In contrast, fluvoxamine-exposed mice did not show alterations in behavior and serotonintransporter levels. Decreasing the dose of fluoxetine resulted in higher survival rates and less dramatic effects on the long-term behavior in the offspring. CONCLUSIONS: These results indicate that prenatal fluoxetine exposure affects fetal development, resulting in cardiomyopathy

The Revised NEO Personality Inventory domains of Neuroticism and Agreeableness are considered factorially distinct despite several intercorrelations between these domains. The genetic correlation, an index of the degree to which these intercorrelations are caused by genetic influences, was estimated using data from 913 monozygotic and 562 dizygotic volunteer twin pairs from Canada, Germany, and Japan. The serotonintransporter gene, 5-HTTLPR, was assayed in a sample of 388 nontwin sibling pairs from the United States to determine the contribution of the serotonintransporter locus to the covariation between the Neuroticism and Agreeableness scales. In all four samples, genetic influences contributed to the covariance of Neuroticism and Agreeableness, with the serotonintransporter gene accounting for 10% of the relationship between these domains.

Monoamine transporters have been implicated in dopamine or serotonin release in response to abused drugs such as methamphetamine or ecstasy (MDMA). In addition, monoamine transporters show substrate-induced inward currents that may modulate excitability and Ca(2+) mobilization, which could also contribute to neurotransmitter release. How monoamine transporters modulate Ca(2+) permeability is currently unknown. We investigate the functional interaction between the human serotonintransporter (hSERT) and voltage-gated Ca(2+) channels (CaV). We introduce an excitable expression system consisting of cultured muscle cells genetically engineered to express hSERT. Both 5HT and S(+)MDMA depolarize these cells and activate the excitation-contraction (EC)-coupling mechanism. However, hSERT substrates fail to activate EC-coupling in CaV1.1-null muscle cells, thus implicating Ca(2+) channels. CaV1.3 and CaV2.2 channels are natively expressed in neurons. When these channels are co-expressed with hSERT in HEK293T cells, only cells expressing the lower-threshold L-type CaV1.3 channel show Ca(2+) transients evoked by 5HT or S(+)MDMA. In addition, the electrical coupling between hSERT and CaV1.3 takes place at physiological 5HT concentrations. The electrical coupling between monoamine neurotransmitter transporters and Ca(2+) channels such as CaV1.3 is a novel mechanism by which endogenous substrates (neurotransmitters) or exogenous substrates (like ecstasy) could modulate Ca(2+)-driven signals in excitable cells.

Full Text Available Abstract Background Genetic variation in the regulatory region of the human serotonintransporter gene (SLC6A4 has been shown to affect brain functionality and personality. However, large heterogeneity in its biological effects is observed, which is at least partially due to genetic modifiers. To gain insight into serotonintransporter (SERT-specific genetic modifiers, we studied an intercross between the Wistar SERT-/- rat and the behaviorally and genetically divergent Brown Norway rat, and performed a QTL analysis. Results In a cohort of >150 intercross SERT-/- and control (SERT+/+ rats we characterized 12 traits that were previously associated with SERT deficiency, including activity, exploratory pattern, cocaine-induced locomotor activity, and abdominal and subcutaneous fat. Using 325 genetic markers, 10 SERT-/--specific quantitative trait loci (QTLs for parameters related to activity and exploratory pattern (Chr.1,9,11,14, and cocaine-induced anxiety and locomotor activity (Chr.5,8 were identified. No significant QTLs were found for fat parameters. Using in silico approaches we explored potential causal genes within modifier QTL regions and found interesting candidates, amongst others, the 5-HT1D receptor (Chr. 5, dopamine D2 receptor (Chr. 8, cannabinoid receptor 2 (Chr. 5, and genes involved in fetal development and plasticity (across chromosomes. Conclusions We anticipate that the SERT-/--specific QTLs may lead to the identification of new modulators of serotonergic signaling, which may be targets for pharmacogenetic and therapeutic approaches.

Full Text Available Some allelic variants of the serotonintransporter linked polymorphic region (5-HTTLPR result in lower levels of expression of the serotonintransporter gene (SLC6A4. These low-expressing (LE alleles are associated with mental-health disorders in a minority of humans that carry them. Humans are not the only primates that exhibit this polymorphism; other species, including some monkeys, also have LE and high-expressing (HE variants of 5-HTTLPR. We propose a behavioral genetic framework to explain the adaptive evolution of this polymorphism in primates, including humans. We hypothesize that both LE and HE alleles are maintained by balancing selection in species characterized by short-term fluctuations in social competition levels. More specifically, we propose that LE carriers benefit from their hypervigilant tendencies during periods of elevated competition, whereas HE homozygotes cope best when competition levels do not deviate from the norm. Thus, both alleles have long-term benefits when competition levels tend to vary substantially over relatively short timescales within a social group. We describe this hypothesis in detail and outline a series of predictions to test it. Some of these predictions are supported by findings in the current literature, while others remain areas of future research.

It is evident that there is a relationship between the brain's serotonin system and obesity. Although it is clear that drugs affecting the serotonin system regulate appetite and food intake, it is unclear whether changes in the serotonin system are cause or consequence of obesity. To determine whether obesogenic eating habits result in reducedserotonintransporter (SERT)-binding in the human hypothalamic region, we included 25 lean, male subjects who followed a 6-week-hypercaloric diet, which were high-fat-high-sugar (HFHS) or high-sugar (HS) with increased meal size or -frequency (=snacking pattern). We measured SERT-binding in the hypothalamic region with SPECT. All hypercaloric diets significantly increased body weight by 3-3.5%. Although there were no differences in total calories consumed between the diets, only a hypercaloric HFHS-snacking diet decreased SERT-binding significantly by 30%. We here show for the first time in humans that snacking may change the serotonergic system increasing the risk to develop obesity.

The serotonintransporter (SERT) mediates clearance of serotonin from the synapse, thereby, regulating extracellular serotonin concentrations. Radioligand uptake techniques are typically used to assess SERT function in tissue and heterologous expression systems. The need for sufficient protein in samples, however, requires use of homogenate preparations, potentially masking effects limited to specific cell populations. 4-(4-(dimethylamino)-styryl)-N-methylpyridinium (ASP+) is a fluorescent monoamine transporter substrate that has been used for real-time monitoring of dopamine and norepinephrine transporter function in single cells. The present live cell imaging studies examine the utility of ASP+ for quantifying hSERT function in HEK-293 and neuroblastoma cells. We show rapid membrane binding and intracellular ASP+ accumulation in hSERT expressing cells. Accumulation is saturable; dependent on temperature and the presence of sodium and chloride in the media, and attenuated by serotonin. Acute or prolonged exposure of cells to serotonin re-uptake inhibitors produces a concentration-dependent decrease in accumulation. Similar effects are produced by PKC activation whereas p38MAPK activation increases ASP+ accumulation. These data demonstrate the validity of ASP+ as a probe for monitoring SERT function in living cells. Alterations in SERT binding and uptake can be quantified in the same cell and use of a within cell design permits analysis of time-related alterations in SERT function. PMID:20524964

Full Text Available Visceral hypersensitivity plays an important role in motor and sensory abnormalities associated with irritable bowel syndrome, but the underlying mechanisms are not fully understood. The present study was designed to evaluate the expression of the 5-HT4 receptor and the serotonintransporter (SERT as well as their roles in chronic visceral hypersensitivity using a rat model. Neonatal male Sprague-Dawley rats received intracolonic injections of 0.5% acetic acid (0.3-0.5 mL at different times between postnatal days 8 and 21 to establish an animal model of visceral hypersensitivity. On day 43, the threshold intensity for a visually identifiable contraction of the abdominal wall and body arching were recorded during rectal distention. Histological evaluation and the myeloperoxidase activity assay were performed to determine the severity of inflammation. The 5-HT4 receptor and SERT expression of the ascending colon were monitored using immunohistochemistry and Western blot analyses; the plasma 5-HT levels were measured using an ELISA method. As expected, transient colonic irritation at the neonatal stage led to visceral hypersensitivity, but no mucosal inflammation was later detected during adulthood. Using this model, we found reduced SERT expression (0.298 ± 0.038 vs 0.634 ± 0.200, P < 0.05 and increased 5-HT4 receptor expression (0.308 ± 0.017 vs 0.298 ± 0.021, P < 0.05. Treatment with fluoxetine (10 mg·kg-1·day-1, days 36-42, tegaserod (1 mg·kg-1·day-1, day 43, or the combination of both, reduced visceral hypersensitivity and plasma 5-HT levels. Fluoxetine treatment increased 5-HT4 receptor expression (0.322 ± 0.020 vs 0.308 ± 0.017, P < 0.01 but not SERT expression (0.219 ± 0.039 vs 0.298 ± 0.038, P = 0.654. These results indicate that both the 5-HT4 receptor and SERT play a role in the pathogenesis of visceral hypersensitivity, and its mechanism may be involved in the local 5-HT level.

Full Text Available Visceral hypersensitivity plays an important role in motor and sensory abnormalities associated with irritable bowel syndrome, but the underlying mechanisms are not fully understood. The present study was designed to evaluate the expression of the 5-HT4 receptor and the serotonintransporter (SERT as well as their roles in chronic visceral hypersensitivity using a rat model. Neonatal male Sprague-Dawley rats received intracolonic injections of 0.5% acetic acid (0.3-0.5 mL at different times between postnatal days 8 and 21 to establish an animal model of visceral hypersensitivity. On day 43, the threshold intensity for a visually identifiable contraction of the abdominal wall and body arching were recorded during rectal distention. Histological evaluation and the myeloperoxidase activity assay were performed to determine the severity of inflammation. The 5-HT4 receptor and SERT expression of the ascending colon were monitored using immunohistochemistry and Western blot analyses; the plasma 5-HT levels were measured using an ELISA method. As expected, transient colonic irritation at the neonatal stage led to visceral hypersensitivity, but no mucosal inflammation was later detected during adulthood. Using this model, we found reduced SERT expression (0.298 ± 0.038 vs 0.634 ± 0.200, P < 0.05 and increased 5-HT4 receptor expression (0.308 ± 0.017 vs 0.298 ± 0.021, P < 0.05. Treatment with fluoxetine (10 mg·kg-1·day-1, days 36-42, tegaserod (1 mg·kg-1·day-1, day 43, or the combination of both, reduced visceral hypersensitivity and plasma 5-HT levels. Fluoxetine treatment increased 5-HT4 receptor expression (0.322 ± 0.020 vs 0.308 ± 0.017, P < 0.01 but not SERT expression (0.219 ± 0.039 vs 0.298 ± 0.038, P = 0.654. These results indicate that both the 5-HT4 receptor and SERT play a role in the pathogenesis of visceral hypersensitivity, and its mechanism may be involved in the local 5-HT level.

The effect of hydrogen peroxide on the active transport of serotonin (5-HT) by human platelets was investigated. Platelets were exposed to either a single dose of H{sub 2}O{sub 2} or to H{sub 2}O{sub 2} generated by the glucose/glucose oxidase or xanthine/xanthine oxidase enzyme systems. H{sub 2}{sub 2} produced a rapid, dose-dependent and time-dependent increase in 5-HT transport which was maximal after a 2 min incubation and decreased with continued incubation. Catalase completely prevented H{sub 2}O{sub 2}-induced stimulation and fluoxetine totally blocked 5-HT uptake into stimulated platelets. The glucose/glucose oxidase and the xanthine/xanthine oxidase generating systems produced a similar response to that of H{sub 2}O{sub 2}. In the xanthine/xanthine oxidase system, superoxide dismutase failed to alter the stimulation, while catalase effectively prevented the response. The kinetics of 5-HT transport indicated that H{sub 2}O{sub 2} treatment did not alter the K{sub m} of 5-HT transport but significantly increased the maximal rate of 5-HT transport. These data demonstrated that exposure of human platelets to H{sub 2}O{sub 2} resulted in a stimulation of the active transport of 5-HT and suggested that H{sub 2}O{sub 2} may function to regulate this process.

Hyperserotonemia; Serotonergic syndrome; Serotonin toxicity; SSRI - serotonin syndrome; MAO - serotonin syndrome ... two medicines that affect the body's level of serotonin are taken together at the same time. The ...

Acute pharmacological elevation of serotonin (5-hydroxytryptamine; 5-HT) activity decreases operant responding for primary reinforcers, suggesting that 5-HT reduces incentive motivation. The mechanism by which 5-HT alters incentive motivation is unknown, but parallel evidence that 5-HT2C receptor agonists also reduce responding for primary reinforcers implicates this receptor as a potential candidate. These experiments examined whether chronic and acute disruptions of serotonintransporter (SERT) activity altered incentive motivation, and whether the 5-HT2C receptor mediated the effects of elevated 5-HT on behavior. To assess incentive motivation, we measured responding for three different reinforcers: a primary reinforcer (saccharin), a conditioned reinforcer (CRf), and an unconditioned sensory reinforcer (USRf). In the chronic condition, responding was compared between SERT knockout (SERT-KO) mice and their wild-type littermates. In the acute condition, responding was examined in wild-type mice following treatment with 10 or 20 mg/kg citalopram, or its vehicle. The ability of the selective 5-HT2C antagonist SB 242084 to prevent the effects of SERT-KO and citalopram on responding was subsequently examined. Both SERT-KO and citalopram reduced responding for saccharin, a CRf, and a USRf. Treatment with SB 242084 enhanced responding for a CRf and a USRf in SERT-KO mice and blocked the effects of citalopram on CRf and USRf responding. However, SB 242084 was unable to prevent the effects of SERT-KO or citalopram on responding for saccharin. These results support a powerful inhibitory function for 5-HT in the control of incentive motivation, and indicate that the 5-HT2C receptor mediates these effects of 5-HT in a reinforcer-dependent manner.

Serotonin levels might alter susceptibility to seizures. Serotonintransporter (5HTT) gene polymorphisms were found to be associated with some forms of epilepsy. Here, we attempted to examine an association between 5HTT VNTR allele variants in a serotonintransporter gene and epileptogenesis in juvenile myoclonic epilepsy (JME) cases. We conducted a case-control candidate gene study evaluating the frequencies of 5HTT VNTR allele variants using SYBR green real-time PCR with melting curve analysis in JME patients and healthy subjects. Forty patients with JME were selected from the Epilepsy Outpatient Clinic of Kasr Al Ainy Hospital, Cairo University, who had been classified according to the electroclinical classification of the ILAE. The control group consisted of 40 healthy Egyptian subjects. The less efficient transcriptional genotypes for 5-HTT polymorphisms were more frequent in JME patients (OR 9.33, CI 2.85-30.60; p value epileptogenesis in JME.

Introduction: Serotonin dysfunction has been linked to a variety of psychiatric diseases; however, an adequate SPECT radioligand to probe the serotonintransporter system has not been successfully developed. The purpose of this study was to characterize and determine the in vivo selectivity of iodine-123-labeled 2{beta}-carbomethoxy-3{beta}-(4'-((Z)-2-iodoethenyl)phenyl)nortropane, [{sup 123}I]p ZIENT, in nonhuman primate brain. Methods: Two ovariohysterectomized female baboons participated in nine studies (one bolus and eight bolus to constant infusion at a ratio of 9.0 h) to evaluate [{sup 123}I]p ZIENT. To evaluate the selectivity of [{sup 123}I]p ZIENT, the serotonintransporter blockers fenfluramine (1.5, 2.5 mg/kg) and citalopram (5 mg/kg), the dopamine transporter blocker methylphenidate (0.5 mg/kg) and the norepinephrine transporter blocker nisoxetine (1 mg/kg) were given at 8 h post-radiotracer injection. Results: In the bolus to constant infusion studies, equilibrium was established by 4-8 h. [{sup 123}I]p ZIENT was 93% and 90% protein bound in the two baboons and there was no detection of lipophilic radiolabeled metabolites entering the brain. In the high-density serotonintransporter regions (diencephalon and brainstem), fenfluramine and citalopram resulted in 35-71% and 129-151% displacement, respectively, whereas methylphenidate and nisoxetine did not produce significant changes (<10%). Conclusion: These findings suggest that [{sup 123}I]p ZIENT is a favorable compound for in vivo SPECT imaging of serotonintransporters with negligible binding to norepinephrine and dopamine transporters.

Overgeneral autobiographical memory (OGM) is a key memory deficit in major depressive disorder (MDD). Much research has examined cognitive mechanisms underlying OGM, but little work has investigated potential neurobiological influences. There is preliminary evidence that a genetic serotonergic vulnerability coupled with depressive symptoms may be associated with other memory impairments, and experimental research suggests a role for serotonin in OGM. We investigated whether a polymorphism in the promoter region of the serotonintransporter gene (5-HTTLPR) was associated with OGM in interaction with a lifetime history of MDD in 370 young adults in a longitudinal study of risk for emotional disorders. There was a significant interaction between 5-HTTLPR genotype and lifetime history of MDD in predicting OGM. Among S allele homozygotes, MDD history was associated with greater OGM, whereas no significant relationship between MDD history and OGM emerged among L carriers. Furthermore, there was evidence that a greater number of S alleles were associated with greater memory specificity in individuals without a history of MDD. Implications for understanding cognitive and biological risk for depression are discussed.

Smokers may use nicotine to self-medicate for situation-specific or person-specific cognitive or affective deficits. Although evidence suggests that nicotine replacement therapy (NRT), relative to placebo, enhances spatial working memory (SWM) in smoking-abstinent smokers with schizophrenia, the extent to which NRT may be helpful in attenuating abstinence-related SWM in other groups with deficits in SWM is unknown. Depressive symptoms are associated with both tobacco smoking and deficits in SWM. Previous studies have found that smoking abstinence increases depressive affect and depression-related hemispheric asymmetries in brain activation. Although the serotonin neurotransmitter system is closely associated with depression and the effects of nicotine, the authors are not aware of any studies that have evaluated the possible role of individual differences in serotonintransporter (5-HTT) genotype and depressive symptoms as moderators of the effects of NRT on SWM. Thus, the current study assessed the effects of NRT (nicotine patch) on SWM in relation to: (1) depressive traits and (2) 5-HTT genotype. Smoking-deprived habitual smokers (N = 64) completed the dot recall test of SWM during counterbalanced and double-blind nicotine and placebo testing sessions. There was a marginal overall effect of NRT on SWM. More importantly, NRT enhanced SWM in 5-HTT short allele carriers, relative to those with two long alleles, and this enhancement in short-allele carriers was greater for individuals with higher levels of depressive symptoms.

Both oxytocin and serotonin modulate affiliative responses to partners and offspring. Animal studies suggest a crucial role of oxytocin in mammalian parturition and lactation but also in parenting and social interactions with offspring. The serotonergic system may also be important through its influence on mood and the release of oxytocin. We examined the role of serotonintransporter (5-HTT) and oxytocin receptor (OXTR) genes in explaining differences in sensitive parenting in a community sample of 159 Caucasian, middle-class mothers with their 2-year-old toddlers at risk for externalizing behavior problems, taking into account maternal educational level, maternal depression and the quality of the marital relationship. Independent genetic effects of 5-HTTLPR SCL6A4 and OXTR rs53576 on observed maternal sensitivity were found. Controlling for differences in maternal education, depression and marital discord, parents with the possibly less efficient variants of the serotonergic (5-HTT ss) and oxytonergic (AA/AG) system genes showed lower levels of sensitive responsiveness to their toddlers. Two-way and three-way interactions with marital discord or depression were not significant. This first study on the role of both OXTR and 5-HTT genes in human parenting points to molecular genetic differences that may be implicated in the production of oxytocin explaining differences in sensitive parenting.

The two main groups of antidepressant drugs, the tricyclic antidepressants (TCAs) and the selective serotonin reuptake inhibitors (SSRIs), as well as several other compounds, act by inhibiting the serotonintransporter (SERT). However, the binding mode and molecular mechanism of inhibition in SERT are not fully understood. In this study, five classes of SERT inhibitors were docked into an outward-facing SERT homology model using a new 4D ensemble docking protocol. Unlike other docking protocols, where protein flexibility is not considered or is highly dependent on the ligand structure, flexibility was here obtained by side chain sampling of the amino acids of the binding pocket using biased probability Monte Carlo (BPMC) prior to docking. This resulted in the generation of multiple binding pocket conformations that the ligands were docked into. The docking results showed that the inhibitors were stacked between the aromatic amino acids of the extracellular gate (Y176, F335) presumably preventing its closure. The inhibitors interacted with amino acids in both the putative substrate binding site and more extracellular regions of the protein. A general structure-docking-based pharmacophore model was generated to explain binding of all studied classes of SERT inhibitors. Docking of a test set of actives and decoys furthermore showed that the outward-facing ensemble SERT homology model consistently and selectively scored the majority of active compounds above decoys, which indicates its usefulness in virtual screening.

Full Text Available OBJECTIVES: Serotonin plays a central role in ejaculation and selective serotonin reuptake inhibitors have been successfully used to treat premature ejaculation. Here, we evaluated the relationship between a polymorphism in the serotonintransporter gene-linked polymorphic region (5-HTTLPR and the response of patients with premature ejaculation to SSRI medication. METHODS: Sixty-nine premature ejaculation patients were treated with 20 mg/d paroxetine for three months. The Intravaginal Ejaculatory Latency Time and International Index of Erectile Function scores were compared with baseline values. The patients were scored as having responded to therapy when a 2-fold or greater increase was observed in Intravaginal Ejaculatory Latency Time compared with baseline values after three months. Three genotypes of 5-HTTLPR were studied: LL, LS and SS. The appropriateness of the allele frequencies in 5-HTTLPR were analyzed according to Hardy-Weinberg equilibrium using the χ2-test. RESULTS: The short (S allele of 5-HTTLPR was significantly more frequent in responders than in nonresponders (p<0.05. Out of the 69 total PE patients, 41 patients (59% responded to therapy. There was no significant difference in the International Index of Erectile Function score at the end of therapy between the responder and nonresponder groups. The frequencies of the L allele and S allele were 20% and 39%, respectively, in the responder group (p<0.05. CONCLUSION: We conclude that premature ejaculation patients with the SS genotype respond well to selective serotonin reuptake inhibitor therapy. Further studies with large patient groups are necessary to confirm this conclusion.

Depression and suicidal behavior are frequently observed in patients with schizophrenia. The serotonintransporter protein regulates serotonergic signaling at synapses and is encoded by a single gene (SLC6A4; Locus Link ID: 6532), located at 17q11.1-q12 with two polymorphic variants (the short and the long allele). The short allele of serotonintransporter gene has been associated with depression and suicidality in individuals who suffered negative life events and with depression in individuals with chronic psychosis.. Subjects were recruited from a genetic study of schizophrenia conducted in Costa Rica. The authors replicated their previous research, using a more narrow phenotype (only schizophrenic subjects) and a more ethnically homogenous sample (only Costa Rican schizophrenic individuals who were not included in the previous study). The authors hypothesized that subjects with at least one copy of the serotonintransporter promoter gene polymorphism (5-HTTLPR) "s" allele would have a greater history of lifetime depression and suicidability rate than those who had an "l/l" genotype. The authors analyzed 155 subjects with a DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) diagnosis of schizophrenia (73% male, age at interview 38.3, SD = 11.23). The genotype distribution was "ss" 58 (37%), "sl" 69 (45%), and "ll" 28 (18%). In the secondary analysis, the authors explored association of the "s" allele with lifetime history of suicide behavior in 173 subjects (18 more subjects than primary analysis because schizophrenic individuals were included regardless of history of depression). The authors found that subjects carrying at least one short allele had a significant increased lifetime risk for depressive syndromes (chi(2) = 5.4, df = 1, P = 0.02; odds ratio [OR] = 2.7, 95% confidence interval [CI] = 1.15-6.3). No association was found for suicidal behavior in the same sample (chi(2) = 0.928, P = 0.629). In conclusion, the genotype at the

The serotonintransporters (SERT) are the primary binding sites for selective serotonin reuptake inhibitors, commonly used antidepressants such as fluoxetine, sertraline, and paroxetine. Imaging of SERT with positron emission tomography and single photon emission computed tomography in humans would provide a useful tool for understanding how alterations of this system are related to depressive illnesses and other psychiatric disorders. In this article the synthesis and characterization of [{sup 125}I]ODAM [(5-iodo-2-(2-dimethylaminomethylphenoxy)-benzyl alcohol, 9)] as an imaging agent in the evaluation of central nervous system SERT are reported. A new reaction scheme was developed for the preparation of compound 9, ODAM, and the corresponding tri-n-butyltin derivative 10. Upon reacting 10 with hydrogen peroxide and sodium[{sup 125}I]iodide, the radiolabeled [{sup 125}I]9 was obtained in good yield (94% yield, radiochemical purity >95%). In an initial binding study using cortical membrane homogenates of rat brain, ODAM displayed a good binding affinity with a value of K{sub i}=2.8{+-}0.88 nM. Using LLC-PK{sub 1} cells specifically expressing the individual transporter (i.e. dopamine [DAT], norepinephrine [NET], and SERT, respectively), ODAM showed a strong inhibition on SERT (K{sub i}=0.12{+-}0.02 nM). Inhibition constants for the other two transporters were lower (K{sub i}=3.9{+-}0.7 {mu}M and 20.0 {+-} 1.9 nM for DAT and NET, respectively). Initial biodistribution study in rats after an intravenous (IV) injection of [{sup 125}I]ODAM showed a rapid brain uptake and washout (2.03, 1.49, 0.79, 0.27, and 0.07% dose/organ at 2, 30, 60, 120, and 240 min, respectively). The hypothalamus region where the serotonin neurons are located exhibited a high specific uptake. Ratios of hypothalamus-cerebellum/cerebellum based on percent dose per gram of these two regions showed values of 0.35, 0.86, 0.86, 0.63, and 0.34 at 2, 30, 60, 120, and 240 min, post-IV injection

Strain differences in immobility time in the forced swimming test were investigated in five strains of mice, namely, ICR, ddY, C57BL/6, DBA/2 and BALB/c mice. There were significant strain differences. The immobility times of ICR, ddY and C57BL/6 mice were longer than those of DBA/2 and BALB/c mice. Immobility times were not significantly related to locomotor activity in these strains. There were also differences in sensitivity to the selective serotonin reuptake inhibitor (SSRI) fluvoxamine. In ICR, ddY and C57BL/6 mice, fluvoxamine did not affect immobility time, while it reduced the immobility time of DBA/2 and BALB/c mice dose-dependently. The noradrenaline reuptake inhibitor desipramine decreased immobility time in all strains of mice. Serotonin (5-HT) transporter binding in the brains of all five strains of mice was also investigated. Analysis of 5-HT transporter binding revealed significant strain differences, being lower in DBA/2 and BALB/c mice than in other strains of mice. The amount of 5-HT transporter binding was correlated to baseline immobility time. However, there was no significant relation between noradrenaline transporter binding and immobility time. These results suggest that the duration of baseline immobility depends on the levels of 5-HT transporter binding, leading to apparent strain differences in immobility time in the forced swimming test. Furthermore, differences in 5-HT transporter binding may cause variations in responses to fluvoxamine.

The inability to associate aversive events with relevant cues (i.e. fear learning) may lead to maladaptive anxiety. To further study the role of the serotonintransporter (SERT) in fear learning, classical fear conditioning was studied in SERT knockout rats (SERT(-/-)) using fear potentiation of the startle reflex. Next, fear acquisition and concomitant development of contextual conditioned fear were monitored during training. To differentiate between developmental and direct effects of reduced SERT functioning, effects of acute and chronic SSRI treatment were studied in adult rats. Considering the known interactions between serotonin and corticotropin-releasing factor (CRF), we studied the effect of the CRFR1 antagonist CP154,526 on behavioral changes observed and determined CRF1 receptor levels in SERT(-/-) rats. SERT(-/-) showed blunted fear potentiation and enhanced contextual fear, which resulted from a deficit in fear acquisition. Paroxetine treatment did not affect acquisition or expression of fear-potentiated startle, suggesting that disturbed fear learning in SERT(-/-) results from developmental changes and not from reduced SERT functioning. Although CRF1 receptor levels did not differ significantly between genotypes, CP154,526 treatment normalized both cue- and contextual fear in SERT(-/-) during acquisition, but not expression of fear-potentiated startle. The disrupted fear acquisition and concomitant increase in contextual conditioned fear-potentiated startle fear in SERT(-/-) resembles the associative learning deficit seen in patients with panic disorder and suggests that normal SERT functioning is crucial for the development of an adequate fear neuro-circuitry. Moreover, the normalization of fear acquisition by CP154,526 suggests a role for central CRF signaling in the generalization of fear.

Background: Many recent studies of serotonintransporter gene by environment effects predicting depression have used stress assessments with undefined or poor psychometric methods, possibly contributing to wide variation in findings. The present study attempted to distinguish between effects of acute and chronic stress to predict depressive…

The inability to associate aversive events with relevant cues (i.e. fear learning) may lead to maladaptive anxiety. To further study the role of the serotonintransporter (SERT) in fear learning, classical fear conditioning was studied in SERT knockout rats (SERT(-/-)) using fear potentiation of the

The LPR and STin2 polymorphisms of the serotonintransporter gene (SLC6A4) were combined into haplotypes that, together with quality of maternal parenting, were used to predict initial levels and linear change in children's (N = 138) noncompliance and aggression from age 18-54 months. Quality of mothers' parenting behavior was observed when…

IntroductionThe role of the serotonintransporter gene polymorphism 5-HTTLPR in attention-deficit/hyperactivity disorder (ADHD) is unclear. Heterogeneity of findings may be explained by gene-environment interactions (GxE), as it has been suggested that S-allele carriers are more reactive to psychoso

The inability to associate aversive events with relevant cues (i.e. fear learning) may lead to maladaptive anxiety. To further study the role of the serotonintransporter (SERT) in fear learning, classical fear conditioning was studied in SERT knockout rats (SERT(-/-)) using fear potentiation of the

A novel fluorescent ligand was synthesized as a high-affinity, high specificity probe for visualizing the serotonintransporter (SERT). The rhodamine fluorophore was extended from an aniline substitution on the 5-position of the dihydroisobenzofuran ring of citalopram (2, 1-(3-(dimethylamino)prop...

Highly efficient acetylcholinesterase (AChE) and serotonintransporter (SERT) dual inhibitors, (S)-4 and (R)-13 were designed and synthesized on the basis of the hypothetical model of AChE active site. Both compounds showed potent inhibitory activities against AChE and SERT. [structure: see text

Previous research demonstrates that carriers of the short allele of the serotonintransporter gene (5-HTTLPR) show both greater susceptibility to depression in response to stressful life events and higher rates of generation of stressful events in response to depression. The current study examines relational security (i.e., self-reported beliefs…

The serotonintransporter (SERT) in attention-deficit hyperactivity disorder (ADHD) patients has not been explored by earlier positron emission tomography (PET) studies. We measured SERT availability in female ADHD patients (n=8) and healthy controls (n=14) with PET and [11C]MADAM as a tracer. No significant group differences in [11C]MADAM binding potential were noted.

Twelve alkyl analogues (1-12) of the high-affinity serotonintransporter (SERT) inhibitor 6-nitroquipazine (6-NQ) were synthesized and studied using in vitro radioligand competition binding assays to determine their binding affinity (Ki ). The putative antidepressant activity of five of the binders with the highest SERT binding affinities was studied by the forced swim and locomotor activity mouse tests. The three-dimensional (3D) structures of 8 and 9 were determined using NOE NMR technique. Flexible docking of the compounds was undertaken to illustrate the binding of the compounds in the SERT model. Our results showed that several of the 6-NQ analogues are high-affinity SERT inhibitors and indicated that the octyl (8), decyl (10) and dodecyl (12) 6-NQ analogues exhibit moderate antidepressant activity.

For the development of new ligands as potential imaging agents for the serotonintransporter (SERT),a series of diphenyl ether derivatives have been synthesized,characterized,and evaluated for their in vitro binding affinities to the SERT. Among the above compounds,2-(2-((dimethylamino)methyl)-4-fluoro-phenoxy)-5-bromobenzenamine (15) and 2-(2-((dimethylamino)methyl)-4-fluorophenoxy)-5-iodobenzene amine (16) show high binding affinities for the SERT with Ki values of 0.28 and 0.20 nmol·L-1,respectively. They can be further labeled with carbon-11,fluorine-18,iodine-123 or bromine-76,and evaluated as useful imaging agents for the SERT. Moreover,the study of the structure-activity relationship (SAR) provides some useful information for the future design of new ligands.

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death in patients with refractory epilepsy. Defects in central control of breathing are important contributors to the pathophysiology of SUDEP, and serotonin (5-HT) system dysfunction may be involved. Here we examined the effect of 5-HT neurone elimination or 5-HT reduction on seizure risk and seizure-induced mortality. Adult Lmx1bf/f/p mice, which lack >99% of 5-HT neurones in the CNS, and littermate controls (Lmx1bf/f) were subjected to acute seizure induction by maximal electroshock (MES) or pilocarpine, variably including electroencephalography, electrocardiography, plethysmography, mechanical ventilation or pharmacological therapy. Lmx1bf/f/p mice had a lower seizure threshold and increased seizure-induced mortality. Breathing ceased during most seizures without recovery, whereas cardiac activity persisted for up to 9 min before terminal arrest. The mortality rate of mice of both genotypes was reduced by mechanical ventilation during the seizure or 5-HT2A receptor agonist pretreatment. The selective serotonin reuptake inhibitor citalopram reduced mortality of Lmx1bf/f but not of Lmx1bf/f/p mice. In C57BL/6N mice, reduction of 5-HT synthesis with para-chlorophenylalanine increased MES-induced seizure severity but not mortality. We conclude that 5-HT neurones raise seizure threshold and decrease seizure-related mortality. Death ensued from respiratory failure, followed by terminal asystole. Given that SUDEP often occurs in association with generalised seizures, some mechanisms causing death in our model might be shared with those leading to SUDEP. This model may help determine the relationship between seizures, 5-HT system dysfunction, breathing and death, which may lead to novel ways to prevent SUDEP. PMID:25107926

N,N-dimethyltryptamine (DMT) is a potent plant hallucinogen that has also been found in human tissues. When ingested, DMT and related N,N-dialkyltryptamines produce an intense hallucinogenic state. Behavioral effects are mediated through various neurochemical mechanisms including activity at sigma-1 and serotonin receptors, modification of monoamine uptake and release, and competition for metabolic enzymes. To further clarify the pharmacology of hallucinogenic tryptamines, we synthesized DMT, N-methyl-N-isopropyltryptamine (MIPT), N,N-dipropyltryptamine (DPT), and N,N-diisopropyltryptamine. We then tested the abilities of these N,N-dialkyltryptamines to inhibit [(3)H]5-HT uptake via the plasma membrane serotonintransporter (SERT) in human platelets and via the vesicle monoamine transporter (VMAT2) in Sf9 cells expressing the rat VMAT2. The tryptamines were also tested as inhibitors of [(3)H]paroxetine binding to the SERT and [(3)H]dihydrotetrabenazine binding to VMAT2. Our results show that DMT, MIPT, DPT, and DIPT inhibit [(3)H]5-HT transport at the SERT with K ( I ) values of 4.00 +/- 0.70, 8.88 +/- 4.7, 0.594 +/- 0.12, and 2.32 +/- 0.46 microM, respectively. At VMAT2, the tryptamines inhibited [(3)H]5-HT transport with K ( I ) values of 93 +/- 6.8, 20 +/- 4.3, 19 +/- 2.3, and 19 +/- 3.1 muM, respectively. On the other hand, the tryptamines were very poor inhibitors of [(3)H]paroxetine binding to SERT and of [(3)H]dihydrotetrabenazine binding to VMAT2, resulting in high binding-to-uptake ratios. High binding-to-uptake ratios support the hypothesis that the tryptamines are transporter substrates, not uptake blockers, at both SERT and VMAT2, and also indicate that there are separate substrate and inhibitor binding sites within these transporters. The transporters may allow the accumulation of tryptamines within neurons to reach relatively high levels for sigma-1 receptor activation and to function as releasable transmitters.

In previous studies, serotonin (5-HT) system disturbance was found involved in a variety of behavioral disorders, psychopathologies, and substance use disorders. A functional polymorphism in the promoter region of the human serotonintransporter gene (5-HTTLPR) was recently identified and the presence of the short (S) allele found to be associated with a lower level of expression of the gene, lower levels of 5-HT uptake, type 2 alcoholism, violence and suicidal behavior. In the present study, 101 heroin addicts (males, West European, Caucasians) and 101 healthy control subjects matched for race and gender, with no history of substance use disorder, have been genotyped. Aggressiveness levels were measured in both heroin addicts and controls utilizing Buss-Durkee-Hostility-Inventory (BDHI). Data about suicide attempt and violent criminal behavior in subject history have been collected. The short-short (SS) genotype frequency was significantly higher among heroin dependent individuals compared with control subjects (P = 0.025). The odds ratio for the SS genotype versus the long-long (LL) genotype frequency was 0.69, 95% Cl (0.49-0.97), when heroin addicts were compared with healthy controls. The SS genotype frequency was significantly higher among violent heroin dependent individuals compared with addicted individuals without aggressive behavior (P = 0.02). BDHI mean total scores and suspiciousness and negativism subscales scores were significantly higher in SS individuals, in comparison with LL subjects, among heroin addicts. No association was found between SS genotype and suicide history. Our data suggest that a decreased expression of the gene encoding the 5-HTT transporter, due to "S" promoter polymorphism, may be associated with an increased risk for substance use disorders, particularly in the subjects with more consistent aggressiveness and impulsiveness.

The serotonintransporter protein (SERT) has been the target for the development of several modern antidepressants with an objective of achieving selectivity over other monoamine transporters, thereby minimising side effects observed in the older generation of tricyclic antidepressants. The clinical selective serotonin reuptake inhibitors (SSRIs) have been shown to be among the most effective therapies in the treatment of depression. However they have clinical disadvantages over other classes of antidepressant drugs such as slow onset of action nausea and sleep disruption. The negative feedback loop attributed to the presynaptic 5-HT(1A) receptors has been implicated in the "time lag" observed in many patients between the administration of the SSRI and its observed therapeutic action. In recent years the focus has been on developing compounds with dual affinity for serotonergic auto-receptors along with an inhibitory activity at SERT. These structurally diverse products promise to be the next generation of anti-depressant medicines. This review presents an analysis of the recently reported structural classes with SSRI activity and rationalises the unique relationship between their molecular properties and biological activities. Specific emphasis is placed on the development of molecular structures with dual serotonergic activity. Recent advances in the design and synthesis of single molecular entities possessing 5-HT reuptake inhibition together with 5-HT(1A), 5-HT(1B), 5-HT(1D), 5-HT(2A), DAT, NET, alpha (2)-adrenoceptor and acetylcholinesterase antagonism are reviewed. The structural studies to identify proposed SERT binding sites together with the role of structure and ligand based design in the development of more effective SSRIs are summarised.

Full Text Available Background and Objectives: This study is designed to understand the pathophysiology of one of the most serious health problems, chronic tension-type headache (CTTH. Two polymorphic sites in serotonintransporter protein gene attracted much interest. These are: the variable number of tandem repeats (VNTR and 5′-flanking promoter region (5-HTTLPR. Materials and Methods: VNTR and 5-HTTLPR polymorphisms were investigated in 126 CTTH patients and 138 healthy control subjects. The patients were being treated with amitripytyline or citalopram or sertraline (SSRI. The polymerase chain reaction (PCR method was used to investigate the polymorphisms in the serotonintransporter protein gene. Results: There were no statistically significant results based on the 5-HTTLPR gene alleles, however, STin 2.12/12 genotype and STin 2.12 allele were seen to predominate the control group. In order to investigate the combined effect of the two polymorphic loci on the 5-HTT gene expression, samples were separated into nine groups. Genotypes (S/S-12/10 and (L/S-12/10 displayed statistically significant frequency in the CTTH group than in the control group. No significant differences were noticed between the 5-HTTLPR and VNTR haplotype groups and success in treatment. Conclusion: It is possible to make reliable comparisons and hypothesis about the homozygous and/or heterozygous presence of S and STin 12/10 alleles which may be in interaction with CTTH. On the other hand, the presence of homozygous L and STin12 alleles may play a protective role against CTTH. It is also possible that heterogeneity among diseases showing the same clinical research will require a lot of effort for individual identification.

The neurotransmitter serotonin (5-HT) controls several physiological functions, and a disturbance of the 5-HT system is implicated in many psychiatric conditions. Seasonal variation has been suggested in the 5-HT system. We investigated within-subject seasonal variation in brain serotonintransporter (SERT) binding with the SERT-ligand [(123)I]ADAM and single photon emission computed tomography (SPECT) in 12 healthy individuals. No systematic variation was found in the midbrain or thalamus areas between scans done in summer and winter. Our results suggest that factors other than season are more important in causing within-subject variation of brain SERT binding between summer and winter.

Neurotransmitter transporters of the SLC6 family of proteins, including the human serotonintransporter (hSERT), utilize Na(+), Cl(-), and K(+) gradients to induce conformational changes necessary for substrate translocation. Dysregulation of ion movement through monoamine transporters has been shown to impact neuronal firing potentials and could play a role in pathophysiologies, such as depression and anxiety. Despite multiple crystal structures of prokaryotic and eukaryotic SLC transporters indicating the location of both (or one) conserved Na(+)-binding sites (termed Na1 and Na2), much remains uncertain in regard to the movements and contributions of these cation-binding sites in the transport process. In this study, we utilize the unique properties of a mutation of hSERT at a single, highly conserved asparagine on TM1 (Asn-101) to provide several lines of evidence demonstrating mechanistically distinct roles for Na1 and Na2. Mutations at Asn-101 alter the cation dependence of the transporter, allowing Ca(2+) (but not other cations) to functionally replace Na(+) for driving transport and promoting 5-hydroxytryptamine (5-HT)-dependent conformational changes. Furthermore, in two-electrode voltage clamp studies in Xenopus oocytes, both Ca(2+) and Na(+) illicit 5-HT-induced currents in the Asn-101 mutants and reveal that, although Ca(2+) promotes substrate-induced current, it does not appear to be the charge carrier during 5-HT transport. These findings, in addition to functional evaluation of Na1 and Na2 site mutants, reveal separate roles for Na1 and Na2 and provide insight into initiation of the translocation process as well as a mechanism whereby the reported SERT stoichiometry can be obtained despite the presence of two putative Na(+)-binding sites.

Neurotransmitter transporters of the SLC6 family of proteins, including the human serotonintransporter (hSERT), utilize Na+, Cl−, and K+ gradients to induce conformational changes necessary for substrate translocation. Dysregulation of ion movement through monoamine transporters has been shown to impact neuronal firing potentials and could play a role in pathophysiologies, such as depression and anxiety. Despite multiple crystal structures of prokaryotic and eukaryotic SLC transporters indicating the location of both (or one) conserved Na+-binding sites (termed Na1 and Na2), much remains uncertain in regard to the movements and contributions of these cation-binding sites in the transport process. In this study, we utilize the unique properties of a mutation of hSERT at a single, highly conserved asparagine on TM1 (Asn-101) to provide several lines of evidence demonstrating mechanistically distinct roles for Na1 and Na2. Mutations at Asn-101 alter the cation dependence of the transporter, allowing Ca2+ (but not other cations) to functionally replace Na+ for driving transport and promoting 5-hydroxytryptamine (5-HT)-dependent conformational changes. Furthermore, in two-electrode voltage clamp studies in Xenopus oocytes, both Ca2+ and Na+ illicit 5-HT-induced currents in the Asn-101 mutants and reveal that, although Ca2+ promotes substrate-induced current, it does not appear to be the charge carrier during 5-HT transport. These findings, in addition to functional evaluation of Na1 and Na2 site mutants, reveal separate roles for Na1 and Na2 and provide insight into initiation of the translocation process as well as a mechanism whereby the reported SERT stoichiometry can be obtained despite the presence of two putative Na+-binding sites. PMID:24293367

The discovery that some serotonin reuptake transporter (SERT) ligands have the potential to act as pro-apoptotic agents in the treatment of cancer adds greatly to their diverse pharmacological application. 4-Methylthioamphetamine (MTA) is a selective ligand for SERT over other monoamine transport......The discovery that some serotonin reuptake transporter (SERT) ligands have the potential to act as pro-apoptotic agents in the treatment of cancer adds greatly to their diverse pharmacological application. 4-Methylthioamphetamine (MTA) is a selective ligand for SERT over other monoamine...... transporters. In this study, a novel library of structurally diverse 4-MTA analogues were synthesised with or without N-alkyl and/or C-alpha methyl or ethyl groups so that their potential SERT-dependent antiproliferative activity could be assessed. Many of the compounds displayed SERT-binding activity as well...

MDMA (3,4-methylenedioxymethamphetamine) or 'Ecstasy' is a widely used recreational drug that produces a state of heightened mood but also cardiovascular and vegetative side-effects. In animals, MDMA releases serotonin and, to a lesser extent, dopamine and norepinephrine. The release of serotonin can be blocked by serotonin uptake inhibitors such as citalopram. It is unknown to what extent this mechanism is also responsible for the physiological side-effects of MDMA seen in humans. We investigated the effect of citalopram pretreatment (40 mg i.v.) on vegetative and cardiovascular effects of MDMA (1.5 mg/kg p.o.) in a double-blind placebo-controlled study in 16 healthy volunteers. MDMA moderately increased blood pressure and heart rate, slightly elevated body temperature and produced a broad range of acute and short-term side-effects. Citalopram reduced all these MDMA-induced physiological changes except for body temperature. These findings suggest that physiological effects of MDMA in humans are partially due to an interaction of MDMA with the serotonin carrier and a subsequent release of serotonin.

The high-affinity tritiated (3H) imipramine binding sites are functionally (and perhaps structurally) associated with the presynaptic neuronal and platelet uptake sites for serotonin. Since there is an excellent correlation between the relative potencies of a series of antidepressants in displacing 3H-imipramine from binding sites in human brain and platelet, we have examined the binding of 3H-imipramine to platelets from 14 depressed patients and 28 age- and sex-matched controls. A highly significant decrease in the number of 3H-imipramine binding sites, with no significant change in the apparent affinity constants, was observed in platelets from the depressed patients compared with the controls. These results, coupled with previous studies showing a significant decrease in the maximal uptake of serotonin in platelets from depressed patients, suggest that an inherited or acquired deficiency of the serotonintransport protein or proteins may be involved in the pathogenesis of depression.

The selective serotonin reuptake inhibitor (SSRI) citalopram (R,S-citalopram) is a racemic compound of two enantiomers. On the basis of in-vitro studies, inhibition of the human serotonintransporter (5-HTT) is achieved by the S-enantiomer (S-citalopram or escitalopram). The aim of the present PET study was to compare 5-HTT occupancy after single equimolar doses (with respect to S-enantiomer) in humans in vivo using R,S-citalopram (20 mg) and S-citalopram (10 mg) using PET and the radioligand [(11)C]MADAM. The design was a single-dose, double-blind, two-way crossover study in eight healthy male subjects. The 5-HTT binding potential at baseline and after single doses of study drugs was used to calculate 5-HTT occupancy in seven brain regions. Serum concentrations of the study drugs were determined in order to calculate the apparent inhibition constant (K(i),(app)), a secondary parameter of interest for the comparison. In all brain regions examined, occupancy was numerically higher after treatment with R,S-citalopram [66+/-19% to 78+/-17% (mean+/-s.d.) depending on the region] than after S-citalopram (59+/-15% to 69+/-13%; overall comparison: F=14.8, d.f.=1, 90, p<0.001). In line with this the apparent inhibition constant was significantly lower for R,S-citalopram than for S-citalopram (overall comparison: F=6.7, d.f.=1, 90, p<0.05). The small but significant difference in occupancy and K(i),(app) found between R,S-citalopram and S-citalopram suggests that not only S-citalopram but also R-citalopram to some degree occupies the 5-HTT in the human brain in vivo.

Animal data suggest that the synthetic drug ecstasy may damage brain serotonin neurons. Previously we reported protracted reductions in the availability of the serotonintransporter (SERT), an index of integrity of the axon terminals of brain serotonergic neurons, in SERT-rich brain regions in current human ecstasy users. Comparison of current ecstasy users and former ecstasy users yielded some evidence that this reduction might be reversible. However, participant selection effects could not be ruled out. Therefore, follow-up examinations were performed in these subjects to test the following a priori hypothesis in a prospective longitudinal design that eliminates participant selection effects to a large extent: availability of the SERT increases towards normal levels when ecstasy use is stopped, and remains unchanged or is further decreased if use is continued. Two follow-up positron emission tomography measurements using the SERT ligand [{sup 11}C](+)McN5652 were completed by 15 current and nine former ecstasy users. All subjects used illicit drugs other than ecstasy, too. The time interval between repeated measurements was about 1 year. The time course of the availability of the SERT was analysed in the following SERT-rich regions: mesencephalon, putamen, caudate and thalamus. Current ecstasy users showed a consistent increase in the availability of the SERT in the mesencephalon during the study (Friedman test: p=0.010), which most likely was caused by a decrease in the intensity of ecstasy consumption (Spearman correlation coefficient -0.725, p=0.002). Former ecstasy users showed a consistent increase in SERT availability in the thalamus (Friedman test: p=0.006). Ecstasy-induced protracted alterations in the availability of the SERT might be reversible. (orig.)

the response to antidepressant therapy. The hSERT contains in the second extracellular loop (EL2) two sites for N-linked glycosylation that are critical for functional transporter expression. Here we examine a non-synonymous single nucleotide polymorphism (SNP) in EL2 that gives rise to a potential third......The human serotonintransporter (hSERT) is responsible for reuptake of serotonin (5-HT) from the synaptic cleft and is target for antidepressant medicine. Differential hSERT activity caused by genetic polymorphisms is believed to affect the risk of developing depression and, moreover, to affect...... cells and primary cultures of cortical neurons. An increase in molecular weight was not observed after removal of glycans with peptide N-glycosidase F (PNGase F). Quantitative analysis of western blots indicated significantly increased total transporter expression ( approximately 30%) for hSERT K201N...

The United States consumes more petroleum-based liquid fuel per capita than any other OECD high-income country—30 percent more than the second-highest country (Canada) and 40 percent more than the third-highest (Luxembourg). The transportation sector accounts for 70 percent of U.S. oil consumption and 30 percent of U.S. greenhouse gas emissions. Taking the externalities associated with high U.S. gasoline consumption as largely given, I focus on understanding the policy tools that seek to redu...

By transfecting mouse fibroblast L-M cells with human genomic DNA, the authors have established and identified several clonal cell lines that stably express a high-affinity serotonin (5-HT)-uptake mechanism absent in untransfected host cells. One such cell line, L-S1, possesses features of 5-({sup 3}H)HT uptake similar to those previously characterized in the central nervous system and blood platelets: (i) specificity for 5-HT; (ii) antagonism by imipramine, a known inhibitor of high-affinity 5-HT uptake; (iii) both Na{sup +} and temperature dependence; (iv) kinetic saturability; and (v) high affinity for 5-HT. This cell line can be used to compare the relative efficacies of known blockers of 5-HT uptake and thereby offers a rapid and reliable assay system for testing novel inhibitors of this system. Since L-S1 contains stably integrated human DNA in its genome, they postulate that the observed 5-HT-uptake system resulted from the expression of human gene(s) coding for the 5-HT transporter. Thus, cell lines such as L-S1 may represent novel means for screening and developing therapeutic agents specific for neutrotransmitter-uptake systems as well as substrate for the cloning and elucidation of the genes encoding the various neurotransmitter transporters.

Serotonintransporters (SERT) are target-sites for commonly used antidepressants, such as fluoxetine, paroxetine, sertraline, and so on. Imaging of these sites in the living human brain may provide an important tool to evaluate the mechanisms of action as well as to monitor the treatment of depressed patients. Synthesis and characterization of an improved SERT imaging agent, ADAM (2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine)(7) was achieved. The new compound, ADAM(7), displayed an extremely potent binding affinity toward SERT (K{sub i}=0.013 nM, in membrane preparations of LLC-PK{sub 1}-cloned cell lines expressing the specific monoamine transporter). ADAM(7) also showed more than 1,000-fold selectivity for SERT over norepinephrine transporter (NET) and dopamine transporter (DAT) (K{sub i}=699 and 840 nM, for NET and DAT, respectively). The radiolabeled compound [{sup 125}I]ADAM(7) showed an excellent brain uptake in rats (1.41% dose at 2 min post intravenous [IV] injection), and consistently displayed the highest uptake (between 60-240 min post IV injection) in hypothalamus, a region with the highest density of SERT. The specific uptake of [{sup 125}I]ADAM(7) in the hypothalamus exhibited the highest target-to-nontarget ratio ([hypothalamus - cerebellum]/cerebellum was 3.97 at 120 min post IV injection). The preliminary imaging study of [{sup 123}I]ADAM in the brain of a baboon by single photon emission computed tomography (SPECT) at 180-240 min post IV injection indicated a specific uptake in midbrain region rich in SERT. These data suggest that the new ligand [{sup 123}I]ADAM(7) may be useful for SPECT imaging of SERT binding sites in the human brain.

Both hallucinogens and 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy") have direct agonistic effects on postsynaptic serotonin(2A) receptors, the key site for hallucinogenic actions. In addition, MDMA is a potent releaser and reuptake inhibitor of presynaptic serotonin....

Introduction: Single photon emission computed tomography (SPECT) imaging of the serotonintransporter (SERT) in the brain is a useful tool for examining normal physiological functions and disease states involving the serotonergic system. The goal of this study was to develop an improved SPECT radiotracer with faster kinetics than the current leading SPECT tracer, [{sup 123}I]ADAM, for selective SERT imaging. Methods: The in vitro binding affinities of (2-(2'-((dimethylamino)methyl)-4'-iodophenylthio)benzenamine) (FlipADAM) (1c), were determined using Hampshire pig kidney cells stably overexpressing the serotonin, norepinephrine (NET) or dopamine transporter (DAT). Localization of [{sup 125}I]FlipADAM (1c) was evaluated through biodistribution and autoradiography in male Sprague Dawley rats, and the specificity of binding was assessed by injecting selective SERT or NET inhibitors prior to [{sup 125}I]FlipADAM (1c). Results: FlipADAM (1c) displayed a high binding affinity for SERT (K{sub i}=1.0 nM) and good selectivity over NET and DAT binding (43-fold and 257-fold, respectively). [{sup 125}I]FlipADAM (1c) successfully penetrated the blood brain barrier, as evidenced by the brain uptake at 2 min (1.75% dose/g). [{sup 125}I]FlipADAM(1c) also had a good target to non-target (hypothalamus/cerebellum) ratio of 3.35 at 60 min post-injection. In autoradiography studies, [{sup 125}I]FlipADAM (1c) showed selective localization in SERT-rich brain regions such as the thalamic nuclei, amygdala, dorsal raphe nuclei and other areas. Conclusion: [{sup 125}I]FlipADAM (1c) exhibited faster clearance from the brain and time to binding equilibrium when compared to [{sup 125}I]2-(2'-((dimethylamino)methyl)-phenylthio)-5-iodophenylamine [{sup 125}I]ADAM (1b) and a higher target to non-target ratio when compared to [{sup 125}I]5-iodo-2-(2'-((dimethylamino)methyl)-phenylthio)benzyl alcohol [{sup 125}I]IDAM (1a). Therefore, [{sup 123}I]FlipADAM (1c) may be an improved

Current SPECT radioligands available for in vivo imaging of the dopamine transporter (DAT) also show affinity for monoamine transporters other than DAT, especially the serotonintransporter (SERT). The effect of this lack of selectivity for in vivo imaging is unknown. In this study, we compared...

In Parkinson's disease (PD), both neuropathological and biochemical studies suggest that serotonin (5-HT) neurons are affected by the disease process. The purpose of this study was to assess the integrity of 5-HT transporters in PD using [I-123]{beta}-CIT (2{beta}-carbomethoxy-3{beta}-(4-iodophenyl)tropane], which binds to both 5-HT and dopamine transporters, and SPECT. Forty-five patients with PD at relatively early stages (Hoehn-Yahr stages I-3) and seven agematched healthy controls were injected with 185-370 MBq(I-123]{beta}-CIT. A total of 15 SPECT scans were acquired over a 24 hr period in each subject using a three-headed system. Time activity curves were obtained in the hypothalamic/midbrain region, where the binding of [I-123] {beta}-CIT is associated primarily with 5-HT transporters, and cerebellum, which was assumed to include only nondisplaceable activity. The parameter k3/k4 (forward/dissociation rate), which is a measure of 5-HT transporter density, was estimated by four noninvasive methods: peak equilibrium ratio (PER) [the ratio of specific binding (hypothalamic/midbrain region-cerebellar activity) to nondisplaceable (cerebella) activity when specific binding reaches a peak], area ratio (the ratio of the areas under the specific binding and nondisplaceable activity curves), k3/k4 obtained using a kinetic two-compartment model [R(2C)], and k3/k4 from a modified graphic method [R(DV)] (Ichise et al., 1996). In the healthy controls, the activity in the hypothalamic/midbrain area generally peaked by 3 hr after tracer injection, then decreased slowly; similar patterns were observed in the PD patients. The k3/k4 values estimated by four different methods in the PD patients did not differ significanlty from those in the healthy controls. In the PD patients, the k3/k4 estimates were not significantly correlated with either Hoehn-Yahr scale or UPDRS (Unified Parkinson's Disease Rating Scale) scores, including total, motor, activities of daily living

The present study examined the association between a measure of sociopathy and 5-HTTLPR genotype in a sample of individuals from Project MATCH, a multi-center alcohol treatment trial. 5-HTTLPR, an insertion/deletion polymorphism in SLC6A4, the gene encoding the serotonintransporter protein, results in functionally distinct long (L) and short (S) alleles. The S allele has been associated with a variety of psychiatric disorders and symptoms including alcohol dependence, but it is unknown wheth...

Early malnutrition has been associated with a high risk of developing obesity, diabetes and cardiovascular diseases in adulthood. In animals, poor perinatal nutrition produces hyperphagia and persistent increased levels of serotonin (5-HT) in the brain. Inasmuch as 5-HT is directly related to the negative regulation of food intake, here we have investigated whether the anorexic effects of 5-HT are altered by protein malnutrition. Pregnant Sprague-Dawley rats were fed ad libitum either a control (20% protein) or a low-protein (8% protein) diet throughout pregnancy and lactation. At weaning, pups received a standard diet and at 35 days their feeding behaviour was evaluated after the administration of DL-fenfluramine (DL-FEN), an anorexic compound that blocks the reuptake of 5-HT and stimulates its release. Male offspring born to protein-restricted dams exhibited significantly decreased body weight and hyperphagia compared with controls. DL-FEN dose-dependently reduced the 1 h chow intake at the onset of the dark cycle in both control and undernourished rats. However, the hypophagic effects of DL-FEN were significantly attenuated in animals submitted perinatally to protein restriction. The stimulatory action of DL-FEN on c-fos immunoreactivity within the paraventricular nucleus of the hypothalamus was also decreased in low-protein-fed rats. Further pharmacological analysis with selective 5-HT(1B) and 5-HT(2C) receptor agonist showed that the reduced anorexic effects of 5-HT in malnourished animals were coupled to a desensitization of 5-HT(1B) receptors. These observations indicate that the hyperphagia associated with metabolic programming is at least partially related to a reduced regulatory function of 5-HT on food intake.

A single imaging gene-environment (IGxE) framework that is able to simultaneously model genetic, neurobiological, and environmental influences on psychopathology outcomes is needed to improve understanding of how complex interrelationships between allelic variation, differences in neuroanatomy or neuroactivity, and environmental experience affect risk for psychiatric disorder. In a longitudinal study of adolescent development we demonstrate the utility of such an IGxE framework by testing whether variation in parental behavior at age 12 altered the strength of an imaging genetics pathway, involving an indirect association between allelic variation in the serotonintransporter gene to variation in hippocampal volume and consequent onset of major depressive disorder by age 18. Results were consistent with the presence of an indirect effect of the serotonintransporter S-allele on depression onset via smaller left and right hippocampal volumes that was significant only in family environments involving either higher levels of parental aggression or lower levels of positive parenting. The previously reported finding of S-allele carriers' increased risk of depression in adverse environments may, therefore, be partly because of the effects of these environments on a neurobiological pathway from the serotonintransporter gene to depression onset that proceeds through variation in hippocampal volume.

Full Text Available Meta-analyses suggest that the serotonintransporter linked polymorphic region (5-HTTLPR short (S allele, relative to the long (L allele, is associated with risk for alcohol dependence, particularly among individuals with early onset antisocial alcoholism. Youth in substance use treatment tend to show antisocial or externalizing behaviors, such as conduct problems, which predict worse treatment outcome. This study examined a pathway in which 5-HTTLPR genotype is associated with externalizing behavior, and the intermediate phenotype of externalizing behavior serves as a link between 5-HTTLPR genotype and substance use treatment outcome in youth. Adolescents (n=142 who were recruited from addictions treatment were genotyped for 5-HTTLPR polymorphisms (S and LG carriers vs. LALA, assessed for externalizing and internalizing behaviors shortly after starting treatment, and followed over 6-months. 5-HTTLPR genotype was not associated with internalizing behaviors, and was not directly associated with 6-month substance use outcomes. However, 5-HTTLPR genotype was associated with externalizing behaviors (S and LG > LALA, and externalizing behaviors predicted alcohol and marijuana problem severity at 6-month follow-up. Results indicated an indirect (p

Full Text Available Previous studies have demonstrated that the serotonintransporter gene-linked polymorphic region (5-HTTLPR affects the recognition of facial expressions and attention to them. However, the relationship between 5-HTTLPR and the perceptual detection of others' facial expressions, the process which takes place prior to emotional labeling (i.e., recognition, is not clear. To examine whether the perceptual detection of emotional facial expressions is influenced by the allelic variation (short/long of 5-HTTLPR, happy and sad facial expressions were presented at weak and mid intensities (25% and 50%. Ninety-eight participants, genotyped for 5-HTTLPR, judged whether emotion in images of faces was present. Participants with short alleles showed higher sensitivity (d' to happy than to sad expressions, while participants with long allele(s showed no such positivity advantage. This effect of 5-HTTLPR was found at different facial expression intensities among males and females. The results suggest that at the perceptual stage, a short allele enhances the processing of positive facial expressions rather than that of negative facial expressions.

Growing evidence supports a major contribution of cortical serotonin (5-hydroxytryptamine, 5-HT) to the modulation of cognitive flexibility and the cognitive inflexibility evident in neuropsychiatric disorders. The precise role of 5-HT and the influence of 5-HT gene variation in mediating this process is not fully understood. Using a touch screen-based operant system, we assessed reversal of a pairwise visual discrimination as an assay for cognitive flexibility. Effects of constitutive genetic or pharmacological inactivation of the 5-HT transporter (5-HTT) on reversal were examined by testing 5-HTT null mice and chronic fluoxetine-treated C57BL/6J mice, respectively. Effects of constitutive genetic loss or acute pharmacological depletion of 5-HT were assessed by testing Pet-1 null mice and para-chlorophenylalanine (PCPA)-treated C57BL/6J mice, respectively. Fluoxetine-treated C57BL/6J mice made fewer errors than controls during the early phase of reversal when perseverative behavior is relatively high. 5-HTT null mice made fewer errors than controls in completing the reversal task. However, reversal in Pet-1 null and PCPA-treated C57BL/6J mice was not different from controls. These data further support an important role for 5-HT in modulating reversal learning and provide novel evidence that inactivating the 5-HTT improves this process. These findings could have important implications for understanding and treating cognitive inflexibility in neuropsychiatric disease.

Anxiety disorders that are the most commonly occurring psychiatric disorders in childhood, are associated with a range of social and educational impairments and often continue into adulthood. Cognitive behaviour therapy (CBT) is an effective treatment option for the majority of cases, although up to 35-45% of children do not achieve remission. Recent research suggests that some genetic variants may be associated with a more beneficial response to psychological therapy. Epigenetic mechanisms such as DNA methylation work at the interface between genetic and environmental influences. Furthermore, epigenetic alterations at the serotonintransporter (SERT) promoter region have been associated with environmental influences such as stressful life experiences. In this study, we measured DNA methylation upstream of SERT in 116 children with an anxiety disorder, before and after receiving CBT. Change during treatment in percentage DNA methylation was significantly different in treatment responders vs nonresponders. This effect was driven by one CpG site in particular, at which responders increased in methylation, whereas nonresponders showed a decrease in DNA methylation. This is the first study to demonstrate differences in SERT methylation change in association with response to a purely psychological therapy. These findings confirm that biological changes occur alongside changes in symptomatology following a psychological therapy such as CBT.

Association studies of the serotonintransporter promoter polymorphism (5-HTTLPR) and negative emotionality (NE) are inconclusive. However, emerging evidence suggests that the association between this polymorphism and NE may be influenced by levels of another temperament trait, positive emotionality (PE). Therefore, this study examined whether the association between the 5-HTTLPR and NE was moderated by PE. A community sample of 413 three-year-old children completed a standardized battery of laboratory tasks designed to tap temperamental emotionality. Children were also genotyped for the 5-HTTLPR. No direct association between 5-HTTLPR genotype and NE was found. However, the interaction of child PE and NE predicted 5-HTTLPR genotype. Furthermore, children with a short allele who were also low in PE had significantly greater NE than children without a short allele or children with high PE. Our findings suggest that the short allele of the 5-HTTLPR is associated with NE only in the context of low PE. Inconsistent links between NE and this gene in previous research may stem from the failure to consider other temperament traits that moderate associations.

Objective Bullying is the act of intentionally and repeatedly causing harm to someone who has difficulty defending him or herself, and is a relatively wide-spread school-age phenomenon. Being the victim of bullying is associated with a broad spectrum of emotional problems; however, not all children who are bullied go on to develop such problems. Method We tested the hypothesis that the relationship between bullying victimization and emotional problems was moderated by variation in the serotonintransporter (5-HTT) gene in 2,232 British children comprising the Environmental Risk (E-Risk) study cohort. Results Our data supported the hypothesis that children's bullying victimization leads to their developing emotional problems, and that genetic variation in the 5-HTTLPR moderates this relationship. Specifically, frequently bullied children with the SS genotype were at greater risk of developing emotional problems at age 12 than children with the SL or LL genotype. Furthermore, we demonstrated that this genetic moderation persisted (a) after controlling for children's pre-victimization emotional problems by assessing intra-individual change in problems between ages 5 and 12 years, and (b) after controlling for other risk factors shared by children growing up in the same family by comparing emotional problems in twins discordant for bullying victimization. Conclusions These findings are further evidence that the 5-HTTLPR moderates the risk of emotional disturbance after exposure to stressful events. PMID:20643316

Recent attempts to understand the biological bases of depression vulnerability have revealed that both the short allele of the serotonintransporter-linked polymorphic region (5-HTTLPR) and activity in the amygdala are associated with depression. Other studies have reported amygdala hyperactivity associated with the 5-HTTLPR short allele, linking the genetic and neuroimaging lines of research and suggesting a mechanism whereby the short allele confers depression risk. However, fewer investigations have examined the associations among depression, 5-HTTLPR variability, and amygdala activation in a single study. The current study thus investigated whether 5-HTTLPR genotype modulates the association between depressive symptoms and amygdala activity among psychiatrically healthy adults. Regional cerebral blood flow was measured with perfusion fMRI during a task-free scan. We hypothesized differential associations between depressive symptoms and amygdala activity among individuals homozygous for the short allele and individuals homozygous for the long allele. Both whole brain analyses and region-of-interest analyses confirmed this prediction, revealing a significant negative association among the long allele group and a trend of positive association among the short allele group. These results complement existing reports of short allele related amygdala hyperactivity and suggest an additional neurobiological mechanism whereby the 5-HTTLPR is associated with psychiatric outcomes.

A variable number of tandem repeats (short (S) vs long (L)) in the promoter region of the serotonintransporter gene (5-HTTLPR) and a functional variant of a single-nucleotide polymorphism (rs25531) in 5-HTTLPR have been recently associated with increased risk for major depressive disorder (MDD). In particular, relative to L/L or LA homozygotes (hereafter referred to as L′ participants), S carriers or Lg-allele carriers (S′ participants) have been found to have a higher probability of developing depression after stressful life events, although inconsistencies abound. Previous research indicates that patients with MDD are characterized by executive dysfunction and abnormal activation within the anterior cingulate cortex (ACC), particularly in situations requiring adaptive behavioral adjustments following errors and response conflict (action monitoring). The goal of this study was to test whether psychiatrically healthy S′ participants would show abnormalities similar to those of MDD subjects. To this end, 19 S′ and 14 L′ participants performed a modified Flanker task known to induce errors, response conflict, and activations in various ACC subdivisions during functional magnetic resonance imaging. As hypothesized, relative to L′ participants, S′ participants showed (1) impaired post-error and post-conflict behavioral adjustments; (2) larger error-related rostral ACC activation; and (3) lower conflict-related dorsal ACC activation. As similar behavioral and neural dysfunctions have been recently described in MDD patient samples, the current results raise the possibility that impaired action monitoring and associated ACC dysregulation may represent risk factors increased vulnerability to depression. PMID:20090673

Culture-gene coevolutionary theory posits that cultural values have evolved, are adaptive and influence the social and physical environments under which genetic selection operates. Here, we examined the association between cultural values of individualism-collectivism and allelic frequency of the serotonintransporter functional polymorphism (5-HTTLPR) as well as the role this culture-gene association may play in explaining global variability in prevalence of pathogens and affective disorders. We found evidence that collectivistic cultures were significantly more likely to comprise individuals carrying the short (S) allele of the 5-HTTLPR across 29 nations. Results further show that historical pathogen prevalence predicts cultural variability in individualism-collectivism owing to genetic selection of the S allele. Additionally, cultural values and frequency of S allele carriers negatively predict global prevalence of anxiety and mood disorder. Finally, mediation analyses further indicate that increased frequency of S allele carriers predicted decreased anxiety and mood disorder prevalence owing to increased collectivistic cultural values. Taken together, our findings suggest culture-gene coevolution between allelic frequency of 5-HTTLPR and cultural values of individualism-collectivism and support the notion that cultural values buffer genetically susceptible populations from increased prevalence of affective disorders. Implications of the current findings for understanding culture-gene coevolution of human brain and behaviour as well as how this coevolutionary process may contribute to global variation in pathogen prevalence and epidemiology of affective disorders, such as anxiety and depression, are discussed.

Existing studies of the effect on infant temperament of the 48 base pair variable number of tandem repeats polymorphism in exon 3 of the dopamine D4 receptor gene, DRD4 VNTR, and the serotonintransporter-linked polymorphic region, 5-HTTLPR, have provided contradictory results, and age seems to be an important factor. The present study investigated the effect of these two polymorphisms on the stability of infant temperament between 4 and 9 months of age. Furthermore, the effect of a recently discovered single nucleotide polymorphism which modulates the 5-HTTLPR (rs25531) was investigated in relation to infant temperament. The study sample consisted of 90 infants, who were assessed by parental report at the two ages under consideration using the Revised Infant Behavior Questionnaire. It was found that infants carrying the 7-repeat allele of the DRD4 VNTR had higher levels of Negative Affect. Furthermore, there was an interaction between DRD4 VNTR and 5-HTTLPR genotype such that infants with the DRD4 VNTR 7-repeat allele and the highest expressing 5-HTTLPR genotype (L(A) L(A) ) had the highest level of Negative Affect. These effects were largely driven by scores on the Falling Reactivity scale. Genetic effects were stable across age. The results emphasize the need for developmental studies of genetic effects on temperament.

The present study examined whether the inhibition of serotonintransporters (SERT) contributes to cocaine- and other local anesthetics-induced convulsions, and which subtypes of 5-HT receptor are involved in the convulsions. For this purpose, cocaine, meprylcaine and lidocaine, all of which have different effects on SERT, were used as convulsants and the effects of serotonin reuptake inhibitors (SSRIs), specific agonists and antagonists for 5-HT receptor subtypes were evaluated in mice. Administration of SSRI, zimelidine, citalopram and fluoxetine, 5-HT(2A,2C) receptor agonist, R(-)-DOI and the 5-HT2C receptor agonists, mCPP, and MK212 resulted in a marked increase in incidence of convulsions and a reduction in the threshold of lidocaine-induced convulsions, while the 5-HT2B receptor agonist, BW723C86, had little influence. On the other hand, SSRI did not affect the measured parameters in meprylcaine- and cocaine-induced convulsions. R(-)-DOI, mCPP, and MK212 reduced the threshold of meprylcaine or cocaine with less extent than the reduction of lidocaine threshold. Incidence of cocaine- and meprylcaine-induced convulsions was significantly reduced by 5-HT(2A,2B,2C) antagonist, LY-53857, and 5-HT2C antagonist, RS 102221. The threshold of cocaine and meprylcaine was significantly increased by both antagonists. 5-HT2A antagonists MDL 11,939 and ketanserin, and 5-HT2B antagonist SB 204741 except at high doses had little effect on cocaine- and meprylcaine-induced convulsions. None of these antagonists altered the parameters of lidocaine-induced convulsions. Pretreatment with fluoxetine but not citalopram increased the plasma concentration of lidocaine. These results suggest that the increase of serotonergic neuronal activity through 5-HT2C receptor stimulation was responsible for increased activity of local anesthetics-induced convulsions and support the involvement of this mechanism in cocaine- and meprylcaine- but not in lidocaine-induced convulsions through their

Full Text Available Abstract Background Although familial clustering of functional dyspepsia (FD has been reported, the role of genetics in the susceptibility to FD is still not well understood. In the present study, the association between serotonintransporter (SERT gene (SLC6A4 polymorphism and FD was explored. Methods Subjects were divided into either a postprandial distress syndrome (PDS group or an epigastric pain syndrome (EPS group according to the Rome III criteria. The healthy controls were those who had visited a hospital for an annual health check-up. The presence of the SLC6A4 promoter polymorphism, 5-hydroxytryptamin transporter gene linked polymorphic region (5-HTTLPR, was then evaluated, and logistic regression analysis was used to test all variables. Results The 5-HTTLPR genotype distribution was 448 SS, 174 SL, and 24 LL in controls and 30 SS, 20 SL, and 3 LL in FD subjects. No significant correlation was found between the 5-HTTLPR genotype and FD. When the genotypes and subtypes of FD were exploratory evaluated, the SL genotype was significantly associated with PDS [odds ratio (OR = 2.24, 95% confidence interval (CI; 1.16-4.32, P = 0.034 after Bonferroni correction] compared to the SS genotype adjusted for sex and age. Comparison of the SS genotype with the SL/LL genotype also showed a significant association of genotype with PDS (OR = 2.32, 95% CI; 1.23-4.37, P = 0.009. Conclusion The present results suggest that 5-HTTLPR L allele may influence the susceptibility to PDS.

Learning from mistakes and prospectively adjusting behavior in response to reward feedback is an important facet of performance monitoring. Dopamine (DA) pathways play an important role in feedback learning and a growing literature has also emerged on the importance of serotonin (5HT) in reward learning, particularly during punishment or reward omission (negative feedback). Cognitive impairments resulting from psychostimulant exposure may arise from altered patterns in feedback learning, which in turn may be modulated by DA and 5HT transmission. We analyzed long-term, off-drug changes in learning from positive and negative feedback and associated striatal DA transporter (DAT) and frontocortical 5HT transporter (SERT) binding in rats pretreated with methamphetamine (mAMPH). Specifically, we assessed the reversal phase of pairwise visual discrimination learning in rats receiving single dose- (mAMPHsingle) vs. escalating-dose exposure (mAMPHescal). Using fine-grained trial-by-trial analyses, we found increased sensitivity to and reliance on positive feedback in mAMPH-pretreated animals, with the mAMPHsingle group showing more pronounced use of this type of feedback. In contrast, overall negative feedback sensitivity was not altered following any mAMPH treatment. In addition to validating the enduring effects of mAMPH on early reversal learning, we found more consecutive error commissions before the first correct response in mAMPH-pretreated rats. This behavioral rigidity was negatively correlated with subregional frontocortical SERT whereas positive feedback sensitivity negatively correlated with striatal DAT binding. These results provide new evidence for the overlapping, yet dissociable roles of DA and 5HT systems in overcoming perseveration and in learning new reward rules.

We evaluated the genotypes of the serotonintransporter gene (5-HTT) in patients with premature ejaculation (PE) to determine the role of genetic factors in the etiopathogenesis of PE and possibly to identify the patient subgroups. A total of 70 PE patients and 70 controls were included in this study. All men were heterosexual, had no other disorders and were either married or in a stable relationship. PE was defined as ejaculation that occurred within 1 min of vaginal intromission. Genomic DNA from patients and controls was analyzed using polymerase chain reaction, and allelic variations of the promoter region of the serotonintransporter gene (5-HTTLPR) were determined. The 5-HTTLPR (serotonintransporter promoter gene) genotypes in PE patients vs. Controls were distributed as follows: L/L 16% vs. 17%, L/S 30% vs. 53% and S/S 54% vs. 28%. We examined the haplotype analysis for three polymorphisms of the 5-HTTLPR gene: LL, LS and SS. The appropriateness of the allele frequencies in the 5-HTTLPR gene was analyzed by the Hardy-Weinberg equilibrium using the χ2-test. The short (S) allele of the 5-HTTLPR gene was significantly more frequent in PE patients than in controls (P<0.05). We suggest that the 5-HTTLPR gene plays a role in the pathophysiology of all primary PE cases. Further studies are needed to evaluate the relationship between 5-HTTLPR gene polymorphism and patient subgroup (such as primary and secondary PE) responses to selective serotonin reuptake inhibitors as well as ethnic differences.

Sex hormones and the serotonergic system interact in the regulation of mood, learning, memory and sexual behaviour. However, the mechanisms have not been fully explored. The serotonintransporter protein (5-HTT) regulates synaptic concentrations of serotonin and is a primary target for selective serotonin reuptake inhibitors. The aim of this study was to explore how estrogen treatment alone or in combination with testosterone affects 5-HTT binding potentials measured by positron emission tomography (PET) in specific brain regions of postmenopausal women. Ten healthy surgically postmenopausal women (years since oophorectomy 7.5 ± 4.0, mean ± SD) underwent PET examinations at baseline, after three months of estrogen treatment (transdermal estradiol 100 μg/24 hours) and after another three months of combined estrogen and testosterone (testosterone undecanoate 40 mg daily) treatment using the radioligand [(11)C] MADAM developed for examination of the serotonintransporter. The 5-HTT binding potentials decreased significantly in several cortical regions, as well as in limbic and striatal regions after both estrogen treatment alone and combined estrogen/testosterone treatment in comparison to baseline. The observed decrease in 5-HTT could either be due to direct effects on serotonintransporter expression or be the result of indirect adaptation to estrogen and /or testosterone effects on synaptic serotonin levels. Although the mechanism still needs further exploration, the study supports the view that gonadal hormones play a role in serotonin regulated mood disorders.

The serotonin [5-HT (5-hydroxytryptamine)] transporter (SERT) controls serotonergic neurotransmission in the brain by rapid clearance of 5-HT from the synaptic cleft into presynaptic neurons. SERTs are primary targets for antidepressants for therapeutic intervention of mood disorders. Our previous studies have identified the involvement of several signalling pathways and protein kinases in regulating SERT function, trafficking and phosphorylation. However, whether Akt/PKB (protein kinase) regulates SERT function is not known. In the present study, we made the novel observation that inhibition of Akt resulted in the down-regulation of SERT function through the regulation of SERT trafficking and phosphorylation. Akt inhibitor Akt X {10-(4'-[N-diethylamino)butyl]-2-chlorophenoxazine} reduced the endogenously phosphorylated Akt and significantly decreased 5-HT uptake and 5-HT-uptake capacity. Furthermore, SERT activity is also reduced by siRNA down-regulation of total and phospho-Akt levels. The reduction in SERT activity is paralleled by lower levels of cell-surface SERT protein, reduced SERT exocytosis with no effect on SERT endocytosis and accumulation of SERT in intracellular endocytic compartments with the most prominent localization to late endosomes and lysosomes. Akt2 inhibitor was more effective than Akt1 inhibitor in inhibiting SERT activity. Inhibition of downstream Akt kinase GSK3α/β (glycogen synthase kinase α/β) stimulates SERT function. Akt inhibition leads to a decrease in SERT basal phosphorylation. Our results provide evidence that Akt regulates SERT function and cell-surface expression by regulating the intracellular SERT distribution and plasma membrane availability, which perhaps may be linked to SERT phosphorylation state. Thus any changes in the activation of Akt and/or GSK3α/β could alter SERT-mediated 5-HT clearance and subsequently serotonergic neurotransmission.

{sup 123}I-labelled mZIENT (2{beta}-carbomethoxy-3{beta}-(3'-((Z)-2-iodoethenyl)phenyl)nortropane) has been developed as a radioligand for the serotonintransporter. The aim of this preliminary study was to assess its whole-body biodistribution in humans and estimate dosimetry. Three healthy controls and three patients receiving selective serotonin reuptake inhibitor (SSRI) therapy for depression were included (two men, four women, age range 41-56 years). Whole-body imaging, brain SPECT imaging and blood and urine sampling were performed. Whole-body images were analysed using regions of interest (ROIs), time-activity curves were derived using compartmental analysis and dosimetry estimated using OLINDA software. Brain ROI analysis was performed to obtain specific-to-nonspecific binding ratios in the midbrain, thalamus and striatum. Initial high uptake in the lungs decreased in later images. Lower uptake was seen in the brain, liver and intestines. Excretion was primarily through the urinary system. The effective dose was estimated to be of the order of 0.03 mSv/MBq. The organ receiving the highest absorbed dose was the lower large intestine wall. Uptake in the brain was consistent with the known SERT distribution with higher specific-to-nonspecific binding in the midbrain, thalamus and striatum in healthy controls compared with patients receiving SSRI therapy. {sup 123}I-mZIENT may be a promising radioligand for imaging the serotonintransporters in humans with acceptable dosimetry. (orig.)

) binding in 57 healthy Scandinavians and related the outcome to season of the year and to the 5-HTTLPR carrier status. Results: We found that the number of daylight minutes at the time of scanning correlated negatively with 5-HTT binding in the putamen and the caudate, with a similar tendency...... in the thalamus, whereas this association was not observed for the midbrain. Furthermore, in the putamen, an anatomic region with relatively dense serotonin innervation, we found a significant gene X daylight effect, such that there was a negative correlation between 5-HTT binding and daylight minutes in carriers...

Unilateral hypoxic-ischemia results in the frequent occurrence of interictal spikes, and occasionally sustained ictal discharges accompanied by a reduction in paired-pulse inhibition within the non-lesioned dentate gyrus. To elucidate the roles of serotonin (5-hydroxytryptamine [5-HT]) in an epileptogenic insult, we investigated the changes in 5-HT receptors and serotonintransporter (5-HTT) immunoreactivities within the lesioned and contralateral hippocampus following unilateral hypoxic-ischemia. During epileptogenic periods following hypoxic-ischemia, both 5-HT(1A) and 5HT(1B) receptor immunoreactivities were decreased within the lesioned and the non-lesioned hippocampus. However, 5-HTT immunoreactivity was transiently increased within the hippocampus bilaterally. These findings indicate that alteration of the 5-HT system results in a "diaschisis" pattern, and may contribute to neuronal death and the development of emotional disorders in epileptic patients accompanied by psychological stress.

Domesticated animals tend to develop a coherent set of phenotypic traits. Tameness could be a central underlying factor driving this, and we therefore selected red junglefowl, ancestors of all domestic chickens, for high or low fear of humans during six generations. We measured basal metabolic rate (BMR), feed efficiency, boldness in a novel object (NO) test, corticosterone reactivity and basal serotonin levels (related to fearfulness) in birds from the fifth and sixth generation of the high- and low-fear lines, respectively (44-48 individuals). Corticosterone response to physical restraint did not differ between selection lines. However, BMR was higher in low-fear birds, as was feed efficiency. Low-fear males had higher plasma levels of serotonin and both low-fear males and females were bolder in an NO test. The results show that many aspects of the domesticated phenotype may have developed as correlated responses to reduced fear of humans, an essential trait for successful domestication.

The serotonintransporter gene (5-HTT) plays a crucial role in serotonergic neurotransmission and has been found to be associated, with varying degrees of significance, with many diseases, including autism. Prior association studies of autism have yielded conflicting results regarding the association between two common 5-HTT polymorphisms, the promoter insertion/deletion (5-HTTLPR) and the intron 2 VNTR (STin2 VNTR). We conducted a systematic review and meta-analysis to test the following hypotheses: (i) there is an association between autism and either or both of the 5-HTTLPR and STin2 VNTR polymorphisms, and (ii) the S allele of 5-HTTLPR and/or the STin2.12 allele of the VNTR are the specific risk alleles for autism. All published family-based and population based studies were examined to determine the overall strength of association between 5-HTT polymorphisms and autism. After exclusion of studies with overlapping samples and studies whose data did not allow for calculation of an odds ratio, 16 studies were included for final analyses, all but two of which used a family-based design. The meta-analysis failed to find a significant overall association between either of the 5-HTT polymorphisms examined and autism. Further, no allelic transmission distortion was found when studies of simplex (11 studies) and multiplex (3 studies) family samples were analyzed separately. However, there was significant heterogeneity by ethnicity; family based studies of US mixed population samples showed preferential transmission of the S allele of 5-HTTLPR (S allele:L allele = 247:183), while there was no allelic distortion among the family-based studies of European and Asian samples.

Human brain oscillations represent important features of information processing and are highly heritable. Gender has been observed to affect association between the 5-HTTLPR (serotonin-transporter-linked polymorphic region) polymorphism and various endophenotypes. This study aimed to investigate the effects of 5-HTTLPR on the spontaneous electroencephalography (EEG) activity in healthy male and female subjects. DNA samples extracted from buccal swabs and resting EEG recorded at 60 standard leads were collected from 210 (101 men and 109 women) volunteers. Spectral EEG power estimates and cortical sources of EEG activity were investigated. It was shown that effects of 5-HTTLPR polymorphism on electrical activity of the brain vary as a function of gender. Women with the S/L genotype had greater global EEG power compared to men with the same genotype. In men, current source density was markedly different among genotype groups in only alpha 2 and alpha 3 frequency ranges: S/S allele carriers had higher current source density estimates in the left inferior parietal lobule in comparison with the L/L group. In women, genotype difference in global power asymmetry was found in the central-temporal region. Contrasting L/L and S/L genotype carriers also yielded significant effects in the right hemisphere inferior parietal lobule and the right postcentral gyrus with L/L genotype carriers showing lower current source density estimates than S/L genotype carriers in all but gamma bands. So, in women, the effects of 5-HTTLPR polymorphism were associated with modulation of the EEG activity in a wide range of EEG frequencies. The significance of the results lies in the demonstration of gene by sex interaction with resting EEG that has implications for understanding sex-related differences in affective states, emotion and cognition.

Mouse strain differences in immobility and in sensitivity to antidepressants have been observed in the forced swimming test (FST) and the tail suspension test (TST). However, the neurotransmitter systems and neural substrates that contribute to these differences remain unknown. To investigate the role of the hippocampal serotonintransporter (5-HTT), we measured baseline immobility and the immobility responses to fluoxetine (FLX) in the FST and the TST in male CD-1, C57BL/6, DBA and BALB/c mice. We observed strain differences in baseline immobility time, with CD-1 mice showing the longest and DBA mice showing the shortest. In contrast, DBA and BALB/c mice showed the highest sensitivity to FLX, whereas CD-1 and C57BL/6 mice showed the lowest sensitivity. Also we found strain differences in both the total 5-HTT protein level and the membrane-bound 5-HTT level (estimated by V max) as follows: DBA>BALB/c>CD-1=C57BL/6. The uptake efficiency of the membrane-bound 5-HTT (estimated by 1/K m) was highest in DBA and BALB/c mice and lowest in CD-1 and C57BL/6 mice. A correlation analysis of subregions within the hippocampus revealed that immobility time was negatively correlated with V max and positively correlated with K m in the hippocampus. Therefore a higher uptake capacity of the membrane-bound 5-HTT in the hippocampus was associated with lower baseline immobility and greater sensitivity to FLX. These results suggest that alterations in hippocampal 5-HTT activity may contribute to mouse strain differences in the FST and the TST.

The aim of this study was to explore the potential of a new selective serotonintransporter (5-HTT) inhibitor, N,N-dimethyl-2-(2-amino-4-methylphenylthio)benzylamine (MADAM, K(i)=1.65 nM), as a PET radioligand for examination of 5-HTT in the nonhuman primate brain. MADAM was radiolabeled by an N-methylation reaction using [(11)C]methyl triflate and the binding was characterized by PET in four cynomolgus monkeys. Metabolite levels in plasma were measured by gradient high-performance liquid chromatography (HPLC). The radiochemical incorporation yield of [(11)C]MADAM was 75-80% and the specific radioactivity at the time of administration was 34-652 GBq/micromol (n=8). The highest uptake of radioactivity was observed in striatum, thalamus, mesencephalon, and the lower brainstem. Lower binding was detected in neocortex and the lowest radioactive uptake was found in the cerebellum. This distribution is in accordance with the known expression of 5-HTT in vitro. The fraction of the total radioactivity in monkey plasma representing unchanged [(11)C]MADAM was 20% at 45 min after injection, as measured by gradient HPLC. Pretreatment measurements, using unlabeled citalopram, GBR 12909, and maprotiline, as well as a displacement measurement, using unlabeled MADAM, confirmed that [(11)C]MADAM binds selectively and reversibly to 5-HTT, and support the use of the cerebellum as reference region. The present characterization of binding in the monkey brain suggests that [(11)C]MADAM is a potential PET radioligand for quantitative studies of 5-HTT binding in the human brain.

The aim of this study was to examine the effects of the SSRI antidepressant drug citalopram on anxiety, depression and mental adjustment to cancer in terminally ill cancer patients, considering also the 5-HTTLPR genetic polymorphism. A group of twenty-one consecutive patients admitted to the hospice of the Casa di Cura Pineta del Carso (Trieste, Italy) with different types of advanced cancer, who were clinically judged to require treatment with an antidepressive drug, was treated with citalopram for two weeks. The response was determined and related to 5-HTTLPR. Citalopram significantly reduced the scores on the depression and anxiety subscales of the Hospital Anxiety and Depression Scale (HADS). When the effects of citalopram were analyzed in relation to the 5-HTTLPR polymorphism, the HADS depression score was significantly decreased only in patients with the "l/l" allelic variant of the serotonintransporter conferring high functional activity, while the score of the Mini-MAC fatalism scale was significantly increased in patients carrying at least one "s" allele. These preliminary findings seem to indicate that two weeks of treatment with citalopram are effective in reducing depressive symptoms in terminally ill cancer patients. Moreover, the effects of citalopram on fatalism as a strategy of mental adaptation to cancer, and on depressive symptoms depend on the allelic variants of the 5-HTTLPR genotype of the patients. These results seem to encourage the examination of a larger patient sample and of different treatment schedules, as well as a more thorough characterization of fatalism as a coping strategy in cancer patients.

Serotonin(5-hydroxytryptamine,5-HT)influences the cortical and subcortical excitatory/inhibitory balance and participates in the pathophysiological processes of epilepsy.The serotonintransporter(5-HTT)is the most important factor in serotonin inactivation.We tested whether 5-HTT polymorphisms are involved in the pathogenesis of epilepsy in Chinese Han population.We did not find a significant difference in the frequencies of genotypes and alleles in the 5-HTT gene-linked polymorphic region(5-HTTLPR)in patients with non-lesional temporal lobe epilepsy and normal controls(P > 0.05).Frequencies of the 5-HTT intren 2 variable number tandem repeat(5-HTTVNTR)12/12 genotype and allele 12 were higher in the patients with non-lesional temporal lobe epilepsy than normal controls(P < 0.01).The odds ratio of affecting non-lesional temporal lobe epilepsy was1.435(95% Cl,1.096 1.880)in patients carrying allele 12(P < 0.05).Although the 5-HTFLPR may not be a genetic locus of non-lesional temporal lobe epilepsy in Chinese Han population,allele 12 in the 5-HTFVNTR may correlate with non-lesional temporal lobe epilepsy.The Stin2.12 allele and12/12 genotype could be predisposing to non-lesional temporal lobe epilepsy.

The folding trajectory of solute carrier 6 (SLC6) family members is of interest because point mutations result in misfolding and thus cause clinically relevant phenotypes in people. Here we examined the contribution of the C terminus in supporting folding of the serotonintransporter (SERT; SLC6A4). Our working hypothesis posited that the amphipathic nature of the C-terminal α-helix (Thr(603)-Thr(613)) was important for folding of SERT. Accordingly, we disrupted the hydrophobic moment of the α-helix by replacing Phe(604), Ile(608), or Ile(612) by Gln. The bulk of the resulting mutants SERT-F604Q, SERT-I608Q, and SERT-I612Q were retained in the endoplasmic reticulum, but their residual delivery to the cell surface still depended on SEC24C. This indicates that the amphipathic nature of the C-terminal α-helix was dispensable to endoplasmic reticulum export. The folding trajectory of SERT is thought to proceed through the inward facing conformation. Consistent with this conjecture, cell surface expression of the misfolded mutants was restored by (i) introducing second site suppressor mutations, which trap SERT in the inward facing state, or (ii) by the pharmacochaperone noribogaine, which binds to the inward facing conformation. Finally, mutation of Glu(615) at the end of the C-terminal α-helix to Lys reduced surface expression of SERT-E615K. A charge reversal mutation in intracellular loop 1 restored surface expression of SERT-R152E/E615K to wild type levels. These observations support a mechanistic model where the C-terminal amphipathic helix is stabilized by an intramolecular salt bridge between residues Glu(615) and Arg(152). This interaction acts as a pivot in the conformational search associated with folding of SERT.

The folding trajectory of solute carrier 6 (SLC6) family members is of interest because point mutations result in misfolding and thus cause clinically relevant phenotypes in people. Here we examined the contribution of the C terminus in supporting folding of the serotonintransporter (SERT; SLC6A4). Our working hypothesis posited that the amphipathic nature of the C-terminal α-helix (Thr603–Thr613) was important for folding of SERT. Accordingly, we disrupted the hydrophobic moment of the α-helix by replacing Phe604, Ile608, or Ile612 by Gln. The bulk of the resulting mutants SERT-F604Q, SERT-I608Q, and SERT-I612Q were retained in the endoplasmic reticulum, but their residual delivery to the cell surface still depended on SEC24C. This indicates that the amphipathic nature of the C-terminal α-helix was dispensable to endoplasmic reticulum export. The folding trajectory of SERT is thought to proceed through the inward facing conformation. Consistent with this conjecture, cell surface expression of the misfolded mutants was restored by (i) introducing second site suppressor mutations, which trap SERT in the inward facing state, or (ii) by the pharmacochaperone noribogaine, which binds to the inward facing conformation. Finally, mutation of Glu615 at the end of the C-terminal α-helix to Lys reduced surface expression of SERT-E615K. A charge reversal mutation in intracellular loop 1 restored surface expression of SERT-R152E/E615K to wild type levels. These observations support a mechanistic model where the C-terminal amphipathic helix is stabilized by an intramolecular salt bridge between residues Glu615 and Arg152. This interaction acts as a pivot in the conformational search associated with folding of SERT. PMID:25869136

The folding trajectory of solute carrier 6 (SLC6) family members is of interest because point mutations result in misfolding and thus cause clinically relevant phenotypes in people. Here we examined the contribution of the C terminus in supporting folding of the serotonintransporter (SERT; SLC6A4). Our working hypothesis posited that the amphipathic nature of the C-terminal α-helix (Thr603–Thr613) was important for folding of SERT. Accordingly, we disrupted the hydrophobic moment of the α-he...

of TM6, Ala419 in the interface between TM8 and extracellular loop (EL) 4, and Leu481 in EL5. The reporter positions were used for time-resolved measurement of conformational changes during 5-HT transport and binding of cocaine and the selective serotonin reuptake inhibitors fluoxetine and escitalopram....... At all reporter positions, fluorescence changes observed upon substrate application were distinctly different from those observed upon inhibitor application, with respect to relative amplitude or direction. Furthermore, escitalopram, fluoxetine, and cocaine induced a very similar pattern of fluorescent...

Introduction: Parkinson's disease (PD) affects both dopaminergic and serotonergic systems. In this study, we simultaneously evaluated dopamine and serotonintransporters in primates using dual-isotope single-photon emission computed tomography (SPECT) imaging and compared the results with traditional single-isotope imaging. Methods: Four healthy and one 6-OHDA-induced PD monkeys were used for this study. SPECT was performed over 4 h after individual or simultaneous injection of [{sup 99m}Tc]TRODAT-1 (a dopamine transporter imaging agent) and [{sup 123}I]ADAM (a serotonintransporter imaging agent). Results: The results showed that the image quality and uptake ratios in different brain regions were comparable between single- and dual-isotope studies. The striatal [{sup 99m}Tc]TRODAT-1 uptake in the PD monkey was markedly lower than that in normal monkeys. The uptake of [{sup 123}I]ADAM in the midbrain of the PD monkey was comparable to that in the normal monkeys, but there were decreased uptakes in the thalamus and striatum of the PD monkey. Conclusions: Our results suggest that dual-isotope SPECT using [{sup 99m}Tc]TRODAT-1 and [{sup 123}I]ADAM can simultaneously evaluate changes in dopaminergic and serotonergic systems in a PD model.

Full Text Available We previously have shown that cue-induced alcohol craving and propensity for higher drinking are modulated by allelic differences in SLC6A4. In an independent study, we characterized a functional polymorphism, rs1042173 (G/T, in the SLC6A4 3′-untranslated region (3′-UTR; the T allele was associated with lower mRNA and protein levels, and the alcohol-dependent (AD individuals carrying the TT genotype showed higher drinking intensity compared with G-allele carriers. Building upon these findings, we hypothesized that the low-expressing TT genotype associated with intense drinking would predict higher craving for alcohol in AD individuals. In this pilot study, we sought to test our hypothesis by examining 34 Hispanic AD volunteers (mean age, 34.8 years for rs1042173 genotype-based (i.e., TT vs. TG/GG (Gx differences in subjective response to alcohol. We employed a human laboratory paradigm and analyzed the data using a linear mixed-effects model to assess treatment, cue procedures, and genotype main effects as well as the two-way interaction effects between them. On subjective urge to drink and crave for a drink, we found a significant main effect of the cue experiment (p ≤ 0.01 and an interaction effect between genotype and cue effects (p < 0.05. TT genotype was associated with higher intensity of drinking and craving for alcohol. Our results not only support the hypothesis that rs1042173 is a genetic marker for cue-induced alcohol craving among AD males but also are suggestive of a neurobiological mechanism associated with the rs1042173-TT genotype that triggers a disproportionate craving in response to alcohol consumption, which in turn may lead to more intense drinking. Future studies with larger sample sizes are needed to characterize the interactive effects of the serotonintransporter-linked polymorphic region (5′-HTTLPR-L-allele reported in our previous study and of the rs1042173-TT genotype on cue-induced alcohol craving.

The tricyclic tropane analogues (1S,3S,6R,10S)-(Z)-10-(benzoyloxymethyl)-9-(3-chloro-4-iodobenzylidene)-7 -azatricyclo[4.3.1.0{sup 3,7}]decane, 1, and (1S,3S,6R,10S)-(Z)-9-(3-chloro-4-iodobenzylidene)-7-azatricyclo[4.3.1.0{sup 3,7}] = decane-10-carboxylic acid methyl ester, 2, have been shown to be potent and selective serotonintransporter (SERT) ligands. They possess nanomolar affinity for the SERT (Ki = 0.06 nM and 1.8 nM respectively) and are suitable for radiolabelling using iodine-123. In the present study we prepared [{sup 123}I]1 and [{sup 123}I]2 from the appropriate tributylstannane precursors using acidic media with chloramine-T as the oxidising agent. The radiochemical yield obtained for [{sup 123}I]1 varied between 50-60% while for [{sup 123}I]2 the range was 65-80%. Both radioligands were obtained with radiochemical purity > 97% and specific activity estimated to be > 185 GBq/{mu}mol. The biodistribution of [{sup 123}I]1 demonstrated low degree of brain penetration at 5 min (0.14%ID/g) with a homogenous distribution. The radioactivity cleared quickly from all brain regions with no preferential localization. In comparison, [{sup 123}I]2 demonstrated on average a higher brain uptake at 5 min (0.5%ID/g). However the distribution of radioactivity was homogenous and cleared to levels similar to [{sup 123}I]1 at 1 hr post-injection. Pre-administration of citalopram failed to show any significant inhibition of [{sup 123}I]2 uptake in the rat brain. The high lipophilicity of 1 and 2 (HPLC-derived log P{sub 7.4} values of 6.41 and 4.25 respectively) and in vivo metabolism, seen by high thyroid uptake would explain the absence of any specific binding observed in the rat brain. In view of these results [{sup 123}I]1 and [{sup 123}I]2 do not appear to be suitable radioligands for in vivo studies of the SERT.

Full Text Available Abstract Background The serotonintransporter gene (5-HTT is a key regulator of serotonergic neurotransmission and has been linked to various psychiatric disorders. Among the genetic variants, polymorphisms in the 5-HTT gene-linked polymorphic region (5-HTTLPR and variable-number-of-tandem-repeat in the second intron (5-HTTVNTR have functional consequences. However, their genetic impact on cortical oscillation remains unclear. This study examined the modulatory effects of 5-HTTLPR (L-allele carriers vs. non-carriers and 5-HTTVNTR (10-repeat allele carriers vs. non-carriers polymorphism on regional neural activity in a young female population. Methods Blood samples and resting state eyes-closed electroencephalography (EEG signals were collected from 195 healthy women and stratified into 2 sets of comparisons of 2 groups each: L-allele carriers (N = 91 vs. non-carriers for 5-HTTLPR and 10-repeat allele carriers (N = 25 vs. non-carriers for 5-HTTVNTR. The mean power of 18 electrodes across theta, alpha, beta, gamma, gamma1, and gamma2 frequencies was analyzed. Between-group statistics were performed by an independent t-test, and global trends of regional power were quantified by non-parametric analyses. Results Among 5-HTTVNTR genotypes, 10-repeat allele carriers showed significantly low regional power at gamma frequencies across the brain. We noticed a consistent global trend that carriers with low transcription efficiency of 5-HTT possessed low regional powers, regardless of frequency bands. The non-parametric analyses confirmed this observation, with P values of 3.071 × 10-8 and 1.459 × 10-12 for 5-HTTLPR and 5-HTTVNTR, respectively. Conclusions and Limitations Our analyses showed that genotypes with low 5-HTT activity are associated with less local neural synchronization during relaxation. The implication with respect to genetic vulnerability of 5-HTT across a broad range of psychiatric disorders is discussed. Given the low frequency of 10

Although 3,4-methytenedioxymethamphetamine (MDMA or ecstasy) has been shown to damage brain serotonin (5-HT) neurons in animals and possibly humans, little is known about the tong-term consequences of MDMA-induced 5-HT neurotoxic Lesions on functions in which 5-HT is involved, such as cognitive func

To identify potential determinants of substrate selectivity in serotonin (5-HT) transporters (SERT), models of human and Drosophila serotonintransporters (hSERT, dSERT) were built based on the leucine transporter (LeuT(Aa)) structure reported by Yamashita et al. (Nature 2005;437:215-223), PBDID 2A65. Although the overall amino acid identity between SERTs and the LeuT(Aa) is only 17%, it increases to above 50% in the first shell of the putative 5-HT binding site, allowing de novo computational docking of tryptamine derivatives in atomic detail. Comparison of hSERT and dSERT complexed with substrates pinpoints likely structural determinants for substrate binding. Forgoing the use of experimental transport and binding data of tryptamine derivatives for construction of these models enables us to critically assess and validate their predictive power: A single 5-HT binding mode was identified that retains the amine placement observed in the LeuT(Aa) structure, matches site-directed mutagenesis and substituted cysteine accessibility method (SCAM) data, complies with support vector machine derived relations activity relations, and predicts computational binding energies for 5-HT analogs with a significant correlation coefficient (R = 0.72). This binding mode places 5-HT deep in the binding pocket of the SERT with the 5-position near residue hSERT A169/dSERT D164 in transmembrane helix 3, the indole nitrogen next to residue Y176/Y171, and the ethylamine tail under residues F335/F327 and S336/S328 within 4 A of residue D98. Our studies identify a number of potential contacts whose contribution to substrate binding and transport was previously unsuspected.

Two novel ligands with 4' substitution on the Phenyl Ring B of biphenylthiol, 5-chloro-2-(2'-((dimethylamino)methyl)-4'-iodophenylthio)benzenamine (7) and 2-(2'-((dimethylamino)methyl)-4'-methoxyphenylthio)-5-iodobenzenamine (8), were prepared and tested as potential serotonintransporter (SERT) imaging agents. The new ligands displayed extremely high binding affinities to SERT (K {sub i}=0.22{+-}0.09 and 0.11{+-}0.04 nM, respectively), with very low binding affinities to dopamine and norepinephrine transporters (K {sub i}>1000 nM). The corresponding [{sup 125}I]7 and [{sup 125}I]8 were successfully prepared from tri-n-butyltin derivatives. They showed good brain uptakes and prolonged retention after intravenous injection in rats (brain uptake was 1.77% and 0.98% dose/g for [{sup 125}I]7, and 0.92% and 0.29% dose/g for [{sup 125}I]8, at 2 and 120 min, respectively). Significantly, [{sup 125}I]7 showed excellent uptake and prolonged retention in the hypothalamus, where SERT concentration was highest. The hypothalamus/cerebellum (HY/CB) ratios (target/background ratios) were 4.24, 7.10, 8.24 and 12.6 at 2, 4, 6 and 12 h, respectively. The HY/CB ratios for [{sup 125}I]8 were 3.97, 5.57 and 5.06 at 1, 2 and 4 h, respectively. Adding the 4'-iodo group to the Phenyl Ring B of Compound (7) appeared to reduce the rate of clearance from the brain, and kinetics favored uptake and retention in the hypothalamus. The localization of [{sup 125}I]7 in the hypothalamus region in the rat brain could be blocked by pretreatment with (+)McN5652, escitalopram and ADAM (2), which are all selective SERT ligands (at 2 mg/kg iv, 5 min pretreatment). Ex vivo autoradiograms of rat brain sections (at 4 h after intravenous injection of [{sup 125}I]7) showed intense labeling in regions of the brain known to have high SERT density. The excellent selective uptake and retention in the hypothalamus region suggest that [{sup 123}I]7 is a potential lead compound for

[{sup 99m}Tc]TRODAT-1 was the first {sup 99m}Tc-labeled imaging agent to show specific binding to dopamine transporters (DAT) in the striatum (STR) of human brain. Additionally, in vitro binding and autoradiographic experiments demonstrated that this tracer also binds to serotonintransporters (SERT) in the midbrain/hypothalamus (MB) area. In this study, [{sup 99m}Tc]TRODAT-1 was investigated as a potentially useful ligand to image SERT in the MB of living brain. A total of eight single-photon emission tomography (SPET) scans were performed in two baboons (Papio anubis) after intravenous (i.v.) injection of 740 MBq (20 mCi) of [{sup 99m}Tc]TRODAT-1 using a triple-head gamma camera equipped with ultra-high-resolution fan-beam collimators (scan time: 0-210 min). In four blocking studies, baboons were pretreated with (+)McN5652 (1 mg/kg, i.v.) or methylphenidate (1 mg/kg, i.v.) to specifically block SERT or DAT, respectively. After co-registration with magnetic resonance images of the same baboon, a region of interest analysis was performed using predefined templates to calculate specific uptake in the midbrain area and the striatum, with the cerebellum as the background region [(MB-CB)/CB, (STR-CB)/CB]. Additionally, two PET scans of the same baboons were performed after i.v. injections of 74-111 MBq (2-3 mCi) of [{sup 11}C](+)McN5652 to identify the SERT sites. In [{sup 99m}Tc]TRODAT-1/SPET scans, the SERT sites in the MB region were clearly visualized. Semiquantitative analysis revealed a specific uptake in MB ([MB-CB]/CB) of 0.30{+-}0.02, which was decreased to 0.040{+-}0.005 after pretreatment with nonradioactive (+)McN5652, a selective SERT ligand. Pretreatment with methylphenidate reduced the specific binding of [{sup 99m}Tc]TRODAT-1 to DAT sites [(STR-CB)/CB] from 2.45{+-}0.13 to 0.32{+-}0.04 without any effect on its binding to SERT sites [(MB-CB)/CB], which was confirmed by the co-registration of the [{sup 11}C](+)McN5652/PET scans. This preliminary study

serotonintransporter (5-HTT) gene allelic variants were shown to be associated with Neuroticism and Harm Avoidance but the results were not replicated in other studies. The current investigation was undertaken in a further attempt to study the relationship between 5-HTT polymorphism and personality traits. to evaluate a spectrum of personality traits, MMPI was administered to a sample including patients with affective disorders (n=114), patients with schizophrenia spectrum illnesses (n=110) and psychiatrically well controls (n=124). All groups were genotyped for VNTR-17 and functional insertion-deletion (5-HTTLPR) polymorphisms. an association was found between 5-HTTLPR polymorphism and scores on three MMPI scales: Psychopathic deviance, Paranoia and Schizophrenia in patients with affective disorders and S chizophrenia in normal subjects. Both affected and control individuals with 'ss' genotype exhibited lower scores on these scales. we demonstrated that functional deletion/insertion allelic variation associated with decreased expression of serotonintransporter ('s' allele or 'ss' genotype) may restrict expression of schizoid traits in normal subjects and patients with affective disorders.

Visceral hypersensitivity plays an important role in motor and sensory abnormalities associated with irritable bowel syndrome, but the underlying mechanisms are not fully understood. The present study was designed to evaluate the expression of the 5-HT{sub 4} receptor and the serotonintransporter (SERT) as well as their roles in chronic visceral hypersensitivity using a rat model. Neonatal male Sprague-Dawley rats received intracolonic injections of 0.5% acetic acid (0.3-0.5 mL at different times) between postnatal days 8 and 21 to establish an animal model of visceral hypersensitivity. On day 43, the threshold intensity for a visually identifiable contraction of the abdominal wall and body arching were recorded during rectal distention. Histological evaluation and the myeloperoxidase activity assay were performed to determine the severity of inflammation. The 5-HT{sub 4} receptor and SERT expression of the ascending colon were monitored using immunohistochemistry and Western blot analyses; the plasma 5-HT levels were measured using an ELISA method. As expected, transient colonic irritation at the neonatal stage led to visceral hypersensitivity, but no mucosal inflammation was later detected during adulthood. Using this model, we found reduced SERT expression (0.298 ± 0.038 vs 0.634 ± 0.200, P < 0.05) and increased 5-HT{sub 4} receptor expression (0.308 ± 0.017 vs 0.298 ± 0.021, P < 0.05). Treatment with fluoxetine (10 mg·kg{sup −1}·day{sup −1}, days 36-42), tegaserod (1 mg·kg{sup −1}·day{sup −1}, day 43), or the combination of both, reduced visceral hypersensitivity and plasma 5-HT levels. Fluoxetine treatment increased 5-HT{sub 4} receptor expression (0.322 ± 0.020 vs 0.308 ± 0.017, P < 0.01) but not SERT expression (0.219 ± 0.039 vs 0.298 ± 0.038, P = 0.654). These results indicate that both the 5-HT{sub 4} receptor and SERT play a role in the pathogenesis of visceral hypersensitivity, and its mechanism may be involved in the local 5-HT

Drugs that selectively inhibit the serotonintransporter (SERT) are widely prescribed for treatment of depression and a range of anxiety disorders. We studied the time course of changes in tryptophan hydroxylase (TPH) in four raphe nuclei after initiation of two different SERT inhibitors, citalopram and fluoxetine. In the first experiment, groups of Sprague-Dawley rats received daily meals of rice pudding either alone (n=9) or mixed with citalopram 5 mg/kg/day (n=27). Rats were sacrificed after 24 h, 7 days or 28 days of treatment. Sections of dorsal raphe nucleus (DRN), median raphe nucleus (MRN), raphe magnus nucleus (RMN) and caudal linear nucleus (CLN) were processed for TPH immunohistochemistry. Citalopram induced a significant reduction in DRN TPH-positive cell counts at 24 h (41%), 7 days (38%) and 28 days (52%). Similar reductions in TPH-positive cell counts were also observed at each timepoint in the MRN and in the RMN. In the MRN, citalopram resulted in significant reductions at 24 h (26%), 7 days (16%) and 28 days (23%). In the RMN, citalopram induced significant reductions of TPH-positive cell counts at 24 h (45%), 7 days (34%) and 28 days (43%). By contrast, no significant differences between control and treatment groups were observed in the CLN at any of the time points that we studied. To investigate whether these changes would occur with other SERT inhibitors, we conducted a second experiment, this time with a 28-day course of fluoxetine. As was observed with citalopram, fluoxetine induced significant reductions of TPH cell counts in the DRN (39%), MRN (38%) and RMN (41%), with no significant differences in the CLN. These results indicate that SERT inhibition can alter the regulation of TPH, the rate limiting enzyme for serotonin biosynthesis. This persistent and regionally specific downregulation of serotonin biosynthesis may account for some of the clinical withdrawal symptoms associated with drugs that inhibit SERT.

Full Text Available Major depressive disorder (MDD is a debilitating disease affecting a wide cross section of people around the world. The current therapy for depression is less than adequate and there is a considerable unmet need for more efficacious treatment. Dopamine has been shown to play a significant role in depression including production of anhedonia which has been one of the untreated symptoms in MDD. It has been hypothesized that drugs acting at all three monoamine transporters including dopamine transporter should provide more efficacious antidepressants activity. This has led to the development of triple reuptake inhibitor D-473 which is a novel pyran based molecule and interacts with all three monoamine transporters. The monoamine uptake inhibition activity in the cloned human transporters expressed in HEK-293 cells (70.4, 9.18 and 39.7 for DAT, SERT and NET, respectively indicates a serotonin preferring triple reuptake inhibition profile for this drug. The drug D-473 exhibited good brain penetration and produced efficacious activity in rat forced swim test under oral administration. The optimal efficacy dose did not produce any locomotor activation. Microdialysis experiment demonstrated that systemic administration of D-473 elevated extracellular level of the three monoamines DA, 5-HT, and NE efficaciously in the dorsal lateral striatum (DLS and the medial prefrontal cortex (mPFC area, indicating in vivo blockade of all three monoamine transporters by D-473. Thus, the current biological data from D-473 indicate potent antidepressant activity of the molecule.

The available data from preclinical and pharmacological studies on the role of the serotonintransporter (5-HTT) support the hypothesis that a dysfunction in brain serotonergic system activity contributes to the vulnerability to affective disorders (AD). 5-HTT is the major site of serotonin reuptake into the presynaptic neuron, and it has been shown that the polymorphic repeat polymorphism in the 5-HTT promotor region (5-HTTLPR) may affect gene-transcription activity. 5-HTT maps to chromosome 17 at position 17q11.17-q12, and the 5-HTTLPR polymorphisms have been extensively investigated in AD with conflicting results. The present study tested the genetic contribution of the 5-HTTLPR polymorphism in a large European multicenter case-control sample, including 539 unipolar (UPAD), 572 bipolar patients (BPAD), and 821 controls (C). Our European collaboration has led to efforts to optimize a methodology that attenuates some of the major limitations of the case-control association approach. No association was found with primary psychiatric diagnosis (UPAD and BPAD) and with phenotypic traits (family history of AD, suicidal attempt, and presence of psychotic features). Our negative findings are not attributable to the lack of statistical power, and may contribute to clarify the role of 5-HTTLPR polymorphism in AD.

The biogenic amine serotonin is a signaling molecule in the gastrointestinal tract, platelets, and nervous tissue. In nervous system, serotonin and its metabolites are under the control of the circadian timing system, but it is not known if daily variations of serotonin exist in the liver. To explore this possibility, we tested if the rhythmic pattern of serotonin metabolism was regulated by daytime restricted feeding (DRF) which is a protocol associated to the expression of the food entraine...

Full Text Available Monoamine transporters are responsible for termination of synaptic signaling and are involved in depression, control of appetite, and anxiety amongst other neurological processes. Despite extensive efforts, the structures of the monoamine transporters and the transport mechanism of ions and substrates are still largely unknown. Structural knowledge of the human serotonintransporter (hSERT is much awaited for understanding the mechanistic details of substrate translocation and binding of antidepressants and drugs of abuse. The publication of the crystal structure of the homologous leucine transporter has resulted in homology models of the monoamine transporters. Here we present extended molecular dynamics simulations of an experimentally supported homology model of hSERT with and without the natural substrate yielding a total of more than 1.5 µs of simulation of the protein dimer. The simulations reveal a transition of hSERT from an outward-facing occluded conformation to an inward-facing conformation in a one-substrate-bound state. Simulations with a second substrate in the proposed symport effector site did not lead to conformational changes associated with translocation. The central substrate binding site becomes fully exposed to the cytoplasm leaving both the Na(+-ion in the Na2-site and the substrate in direct contact with the cytoplasm through water interactions. The simulations reveal how sodium is released and show indications of early events of substrate transport. The notion that ion dissociation from the Na2-site drives translocation is supported by experimental studies of a Na2-site mutant. Transmembrane helices (TMs 1 and 6 are identified as the helices involved in the largest movements during transport.

Epidemiological studies have revealed a strong genetic contribution to the risk for depression. Both reduced hippocampal serotonin neurotransmission and brain-derived neurotrophic factor (BDNF) levels have been associated with increased depression vulnerability and are also regulated during aging...... density. Hippocampal BDNF protein levels were measured by ELISA. An exacerbated age-related loss of serotonin fiber density specific for the CA1 area was observed in the cLH animals, whereas reduced hippocampal BDNF levels were seen in young and old cLH when compared with age-matched cNLH controls...

Serotonergic signaling is considered critical for an appropriate adaptation to stress. We have previously observed that in healthy volunteers, prefrontal serotonintransporter (SERT) binding is positively associated with hypothalamic-pituitary-adrenal (HPA)-axis output in terms of the cortisol...

Gene-environment studies on adolescents' peer contexts are important for understanding the interplay between biological and social antecedents of adolescent psychopathology. To this end, this study examined the roles of serotonintransporter (5-HTTLPR) and preadolescent and early adolescent peer rej

The interaction between childhood maltreatment and the serotonintransporter (5-HTT) gene linked polymorphic region has been associated with increased risk to develop major depression. This Gene x Environment interaction has furthermore been linked with increased levels of anxiety and glucocorticoid

The transporters for the neurotransmitters serotonin and dopamine (SERT and DAT, respectively) are targets for drugs used in the treatment of mental disorders and widely used drugs of abuse. Studies of prokaryotic homologues have advanced our structural understanding of SERT and DAT, but it still...

Preterm birth and Neonatal Intensive Care Unit (NICU) stay are early adverse stressful experiences, which may result in an altered temperamental profile. The serotonintransporter gene ("SLC6A4"), which has been linked to infant temperament, is susceptible to epigenetic regulation associated with early stressful experience. This study…

The serotonintransporter (5-HTT) is of great significance in the control of the serotonergic system, and its expression is known to be upregulated in psoriasis, a chronic or recurrent inflammatory skin disease. We investigated a possible association between the 5-HTT gene-linked polymorphic region (5-HTTLPR) and psoriasis in a Thai population. One hundred and fifty-six psoriatic patients and 156 unrelated healthy controls from Bangkok were genotyped using PCR. We found no overall differences in genotype distributions or allele frequencies between the two groups. In addition, when subgroups of psoriatic patients classified by either onset or severity were analyzed, no significant association between this polymorphism and any subgroup was observed. We conclude that 5-HTTLPR is not associated with susceptibility to psoriasis in this Thai population.

Full Text Available Molecular motors are fundamental to neuronal morphogenesis and function. However, the extent to which molecular motors are involved in higher brain functions remains largely unknown. In this study, we show that mice deficient in the kinesin family motor protein KIF13A (Kif13a−/− mice exhibit elevated anxiety-related behavioral phenotypes, probably because of a reduction in 5HT1A receptor (5HT1AR transport. The cell-surface expression level of the 5HT1AR was reduced in KIF13A-knockdown neuroblastoma cells and Kif13a−/− hippocampal neurons. Biochemical analysis showed that the forkhead-associated (FHA domain of KIF13A and an intracellular loop of the 5HT1AR are the interface between the motor and cargo vesicles. A minimotor consisting of the motor and FHA domains is able to transport 5HT1AR-carrying organelles in in vitro reconstitution assays. Collectively, our results suggest a role for this molecular motor in anxiety control.

The serotonintransporter gene-linked polymorphic region (5-HTTLPR) has been implicated in moderating vulnerability to stress-related psychopathology upon exposure to environmental adversity. A recent meta-analysis suggests a potential biological pathway conveying genotype-dependent stress sensitivity by demonstrating a small, but significant association of 5-HTTLPR and cortisol stress reactivity. An arguably more potent approach to detect larger effects when investigating the 5-HTTLPR stress sensitivity hypothesis is to account for both genetic and epigenetic variation in the serotonintransporter gene (SLC6A4). Here, we applied this approach in an experimental setting. Two hundred healthy adults were exposed to a laboratory stressor (Trier Social Stress Test) and cortisol response patterns were assessed as a function of 5-HTTLPR and DNA methylation profiles in SLC6A4. Specifically, we analyzed 83 CpG sites within a 799-bp promoter-associated CpG island of SLC6A4 using a highly sensitive bisulfite pyrosequencing method. Our results suggest that SLC6A4 methylation levels significantly moderate the association of 5-HTTLPR and cortisol stress reactivity. For individuals displaying low levels of SLC6A4 methylation, the S allele relates to increased cortisol stress reactivity in a dose-dependent fashion accounting for 7-9% of the variance in the endocrine stress response. By contrast, no such effect occurred under conditions of high SLC6A4 methylation, indicating that epigenetic changes may compensate for genotype-dependent differences in stress sensitivity. Studying epigenetic markers may advance gene-environment interaction research on 5-HTTLPR as they possibly capture the net effects of environmental influences relevant for stress-related phenotypes under serotonergic control.

Full Text Available The neurotransmitter serotonin (5-HT plays an important role in both the peripheral and central nervous systems. The biosynthesis of serotonin is regulated by two rate-limiting enzymes, tryptophan hydroxylase-1 and -2 (TPH1 and TPH2. We used a gene-targeting approach to generate mice with selective and complete elimination of the two known TPH isoforms. This resulted in dramatically reduced central 5-HT levels in Tph2 knockout (TPH2KO and Tph1/Tph2 double knockout (DKO mice; and substantially reduced peripheral 5-HT levels in DKO, but not TPH2KO mice. Therefore, differential expression of the two isoforms of TPH was reflected in corresponding depletion of 5-HT content in the brain and periphery. Surprisingly, despite the prominent and evolutionarily ancient role that 5-HT plays in both vertebrate and invertebrate physiology, none of these mutations resulted in an overt phenotype. TPH2KO and DKO mice were viable and normal in appearance. Behavioral alterations in assays with predictive validity for antidepressants were among the very few phenotypes uncovered. These behavioral changes were subtle in the TPH2KO mice; they were enhanced in the DKO mice. Herein, we confirm findings from prior descriptions of TPH1 knockout mice and present the first reported phenotypic evaluations of Tph2 and Tph1/Tph2 knockout mice. The behavioral effects observed in the TPH2 KO and DKO mice strongly confirm the role of 5-HT and its synthetic enzymes in the etiology and treatment of affective disorders.

rate, of [3H]S-citalopram from human SERT, is retarded by the presence of serotonin, as well as by several antidepressants, when present in the dissociation buffer. Dissociation of [3H]S-citalopram from SERT is most potently inhibited by S-citalopram followed by R...... is independent of temperature, or the presence of Na+ in the dissociation buffer. Dissociation of [3H]S-citalopram from a complex with the SERT double-mutant, N208Q/N217Q, which has been suggested to be unable to self-assemble into oligomeric complexes, is retarded to an extent similar...

Full Text Available Abstract Background Bulimia Nervosa (BN is believed to be caused by an interaction of genetic and environmental factors. Previous studies support the existence of a bulimia-related endophenotype as well as disturbances in serotonin (5-HT transmission. We studied serotonintransporter (SERT binding in BN, and to investigate the possibility of a SERT-related endophenotype for BN, did this in a sample of female twins. We hypothesized clearly reduced SERT binding in BN women as opposed to healthy women, and intermediate SERT binding in unaffected co-twins. Methods We studied 13 female twins with BN (9 with purging and 4 with non-purging BN and 25 healthy women, including 6 healthy twin sisters of BN patients and 19 women from 10 healthy twin pairs. [123I]ADAM, a selective SERT radioligand for single photon emission tomography (SPET imaging, was used to assess SERT availability in the midbrain and the thalamus. Results No differences in SERT binding were evident when comparing the BN women, their unaffected co-twins and the healthy controls (p = 0.14. The healthy sisters of the BN patients and the healthy control women had similar SERT binding in both brain regions. In a post hoc subgroup analysis, the purging bulimics had higher SERT binding than the healthy women in the midbrain (p = 0.03, but not in the thalamus. Conclusion Our finding of increased SERT binding in the midbrain in the purging BN women raises the possibility that this subgroup of bulimics might differ in serotonergic function from the non-purging ones. The similarity of the unaffected co-twins and the healthy controls doesn't support our initial assumption of a SERT-related endophenotype for BN. Due to the small sample size, our results need to be interpreted with caution and verified in a larger sample.

Full Text Available The serotonintransporter length polymorphism (5-HTTLPR short allele (5-HTTLPR-s has been associated with differential susceptibility for anxiety and depression in multiple psychiatric disorders. 5-HTTLPR-s modifies the serotonergic systems that support emotion and behavioral regulation by reducing gene expression, which slows the reuptake of serotonin, and is associated with distinct morphological and functional effects. Serotonergic systems are also shown to be dysfunctional in behavioral variant frontotemporal dementia (bvFTD, a disease characterized by marked socioemotional dysfunction. However, studies of 5-HTTLPR-s effects in bvFTD have been inconsistent. Our objective was to investigate the patterns of gray matter volume by 5-HTTLPR-s genotype in both healthy older controls and bvFTD patients. We performed voxel-based morphometry of 179 cognitively normal older adults and 24 bvFTD cases to determine brain changes associated with dose (0/1/2 of 5-HTTLPR-s allele. 5-HTTLPR-s frequency did not differ between controls and bvFTD. We found a significant interaction effect whereby carrying more 5-HTTLPR-s alleles in bvFTD was associated with smaller volume in left inferior frontal gyrus (T = 4.86, PFWE = 0.03 and larger volume in right temporal lobe (T = 5.01, PFWE = 0.01. These results suggest that the 5-HTTLPR-s allele differentially influences brain morphology in bvFTD. We propose that patients with bvFTD and 5-HTTLPR-s have altered volumes in regions that support socioemotional behavior, which may be a developmental or disease-related compensation for altered serotonergic activity.

and amphetamine. Seminal advances in the understanding of the structure and function of this transporter family have recently been accomplished by structural studies of a bacterial transporter, as well as medicinal chemistry and pharmacological studies of mammalian transporters. This feature article focuses...

The 5-hydroxy tryptamine transporter (5-HTT) gene has been previously implicated in lithium response, but the roles of the triallelic 5-HTT linked promoter region (5-HTTLPR) and variable number tandem repeats in the second intron [serotonintransporter intron 2 (STin2)] have not been reported. We examined these polymorphisms in 122 patients with bipolar I disorder, among which 49 patients were classified as good responders, 49 as nonresponders, and 24 as partial responders to lithium prophylaxis. We observed significant variation in the genotype frequencies of STin2 polymorphism among the response groups (P=0.02). There was also a significant association of haplotype consisting of the S allele of 5-HTTLPR and 10 repeat allele of STin2 with lithium response (P=0.01) and no such relationship was found with 5-HTTLPR variants. Our data support preliminary information of a possible association of STin2 and its combined effect with 5-HTTLPR variants with lithium response and also suggest that lithium is likely to be more effective for patients carrying 5-HTT polymorphisms associated with reduced transcriptional activity.

Full Text Available The ability to identify predictors of aversive events allows organisms to appropriately respond to these events, and failure to acquire these fear contingencies can lead to maladaptive contextual anxiety. Recently, preclinical studies demonstrated that the corticotropin-releasing factor and serotonin systems are interactively involved in adaptive fear acquisition. Here, 150 healthy medication-free human subjects completed a cue and context fear conditioning procedure in a virtual reality environment. Fear potentiation of the eyeblink startle reflex (FPS was measured to assess both uninstructed fear acquisition and instructed fear expression. All participants were genotyped for polymorphisms located within regulatory regions of the corticotropin releasing hormone receptor 1 (CRHR1 - rs878886 and the serotonintransporter (5HTTLPR. These polymorphisms have previously been linked to panic disorder and anxious symptomology and personality, respectively. G-allele carriers of CRHR1 (rs878886 showed no acquisition of fear conditioned responses (FPS to the threat cue in the uninstructed phase, whereas fear acquisition was present in C/C homozygotes. Moreover, carrying the risk alleles of both rs878886 (G-allele and 5HTTLPR (short allele was associated with increased FPS to the threat context during this phase. After explicit instructions regarding the threat contingency were given, the cue FPS and context FPS normalized in all genotype groups. The present results indicate that genetic variability in the corticotropin-releasing hormone receptor 1, especially in interaction with the 5HTTLPR, is involved in the acquisition of fear in humans. This translates prior animal findings to the human realm.

The human brainstem is a complex structure with several small nuclei and neural pathways of interest in the pathophysiology of central nervous system (CNS) disorders. In common with other monoaminergic systems, serotoninergic neurons originate from a group of nuclei located in the brainstem. The present study was designed to validate a user-independent approach for a detailed in vivo quantification of serotonintransporter (5-HTT) availability in the human brainstem using a template-based approach that consisted of three steps. First, 3T-MR images and parametric binding potential (BPND) [(11)C]MADAM images of ten healthy subjects were used to generate a PET template of 5-HTT availability. In the second step, volumes of interest (VOIs) for different brainstem nuclei were obtained using a method in which VOIs are initially delineated on MRI images using anatomical landmarks and then are finally tailored on the distribution of 5-HTT binding using a thresholding approach applied to the 5-HTT template. In the final step, the VOIs were transformed and applied individually to BPND images of 16 healthy subjects (14M/2F, 20-64years). The in vivo distribution of BPND values obtained with the template-based method were in good agreement with an individual-based approach taken as gold standard. Results were also in agreement with 5-HTT quantification using in vitro binding data obtained with autoradiography (ARG) studies using [(3)H]MADAM. The proposed template-based method can be applied to PET data acquired in several CNS disorders in which serotonin neurons in the brainstem might be affected.

Serotonintransporters (SERT) in the brain play an important role in normal brain function. Selective serotonin reuptake inhibitors such as fluoxetine, sertraline, paroxetine, escitalopram, etc., specifically target SERT binding in the brain. Development of SERT imaging agents may be useful for studying the function of SERT by in vivo imaging. A one-step preparation of [(18)F]FPBM, 2-(2'-(dimethylamino)methyl)-4'-(3-([(18)F]fluoropropoxy)phenylthio)benzenamine, for positron emission tomography (PET) imaging of SERT binding in the brain was achieved. An active OTs intermediate, 9, was reacted with [(18)F]F(-)/K222 to produce [(18)F]FPBM in one step and in high radiochemical yield. This labeling reaction was evaluated and optimized under different temperatures, bases, solvents, and varying amounts of precursor 9. The radiolabeling reaction led to the desired [(18)F]FPBM in one step and the crude product was purified by HPLC purification to give no-carrier-added [(18)F]FPBM (radiochemical yield, 24-33%, decay corrected; radiochemical purity >99%). PET imaging studies in normal monkeys (n=4) showed fast, pronounced uptakes in the midbrain and thalamus, regions known to be rich in SERT binding sites. A displacement experiment with escitalopram (5mg/kg iv injection at 30min after [(18)F]FPBM injection) showed a rapid and complete reversal of SERT binding, suggesting that binding by [(18)F]FPBM was highly specific and reversible. A one-step radiolabeling method coupled with HPLC purification for preparation of [(18)F]FPBM was developed. Imaging studies suggest that it is feasible to use this method to prepare [(18)F]FPBM for in vivo PET imaging of SERT binding in the brain.

ABSTRACT: BACKGROUND: The serotonin (5-hydroxytryptamin; 5-HT) system has a central role in the circuitry of cognition and emotions. Multiple lines of evidence suggest that genetic variation in the serotonintransporter gene (SLC6A4; 5-HTT) is associated with schizophrenia and suicidal behavior. ...... SLC6A4 appears to be involved in suicidal ideation among patients with schizophrenia. Independent replication is needed before more firm conclusions can be drawn.......ABSTRACT: BACKGROUND: The serotonin (5-hydroxytryptamin; 5-HT) system has a central role in the circuitry of cognition and emotions. Multiple lines of evidence suggest that genetic variation in the serotonintransporter gene (SLC6A4; 5-HTT) is associated with schizophrenia and suicidal behavior....... In this study, we wanted to elucidate whether SLC6A4 variations is involved in attempted suicide among patients with schizophrenia in a Scandinavian case-control sample. METHODS: Patients diagnosed with schizophrenia from three Scandinavian samples were assessed for presence or absence of suicide attempts...

Dysfunction of medullary serotonin (5-HT)-mediated respiratory and autonomic function is postulated to underlie the pathogenesis of the majority of sudden infant death syndrome (SIDS) cases. Several studies have reported an increased frequency of the LL genotype and L allele of the 5-HT transporter (5-HTT) gene promoter polymorphism (5-HTTLPR), which is associated with increased transcriptional activity and 5-HT transport in vitro, in SIDS cases compared with controls. These findings raise the possibility that this polymorphism contributes to or exacerbates existing medullary 5-HT dysfunction in SIDS. In this study, we tested the hypothesis that the frequency of LL genotype and L allele are higher in 179 SIDS cases compared with 139 controls of multiple ethnicities in the San Diego SIDS Dataset. We observed no significant association of genotype or allele with SIDS cases either in the total cohort or on stratification for ethnicity. These observations do not support previous findings that the L allele and/or LL genotype of the 5-HTTLPR are associated with SIDS.

Dysfunction of medullary serotonin (5-HT)-mediated respiratory and autonomic function is postulated to underlie the pathogenesis of the majority of sudden infant death syndrome (SIDS) cases. Several studies have reported an increased frequency of the LL genotype and L allele of the 5-HT transporter (5-HTT) gene promoter polymorphism (5-HTTLPR), which is associated with increased transcriptional activity and 5-HT transport in vitro, in SIDS cases compared with controls. These findings raise the possibility that this polymorphism contributes to or exacerbates existing medullary 5-HT dysfunction in SIDS. In this study, we tested the hypothesis that the frequency of LL genotype and L allele are higher in 179 SIDS cases compared with 139 controls of multiple ethnicities in the San Diego SIDS Dataset. We observed no significant association of genotype or allele with SIDS cases either in the total cohort or on stratification for ethnicity. These observations do not support previous findings that the L allele and/or LL genotype of the 5-HTTLPR are associated with SIDS. PMID:20661167

-ray structure of the closely related amino acid transporter, Aquifex aeolicus leucine transporter (LeuT), provides an opportunity to develop a three-dimensional model of the structure of SERT. We present herein a homology model of SERT using LeuT as the template and containing escitalopram as a bound ligand...

SERT. X-ray crystal structures of the bacterial amino acid transporter LeuT and the Drosophila melanogaster dopamine transporter were used to build homology models of hSERT. Comparative modeling and ligand docking suggest that vortioxetine can adopt several distinct binding modes within the central...

To address the development of early anxiety disorders across the lifespan, the High USV line of rats was bred based on rates of infant ultrasonic vocalization in the 40-50 kHz range of predominant frequencies (USV) to maternal separation at postnatal day (P) 10. In this study, rates of USV in High line infants (pups: Postnatal Day 11+/-1) were compared to those of randomly-bred controls in response to EPIX compound PRX-00023, a unique serotonin (5-HT) agonist, acting exclusively at the 5-HT1A receptor, or buspirone, a nonspecific 5HT1A agonist. After testing, pups were examined for sedation and other drug-related effects. The results indicated that all doses of buspirone reduced USV rates in isolation, consistent with other reports. PRX-00023 significantly reduced USV rates at the lowest doses (0.01-0.05 mg/kg). None of the PRX-00023 doses produced sedation, whereas all but the lowest dose of buspirone (0.1 mg/kg) produced sedation effects. The results suggest that this compound alleviates infantile anxiety-like behavior with great specificity in rats bred for high anxiety/depressive phenotypes by selectively targeting 5-HT1A receptors, possibly by both pre- and post-synaptic mechanisms.

Obsessive compulsive disorder (OCD) is a psychiatric disorder characterized by obsessive ideas and compulsive behaviors. Genetic studies have centered on candidate genes involved in OCD etiology related to serotonergic and dopaminergic systems. In this study, the relationship between cathechol-O-methyltransferase (COMT) -287A/G (rs2097063), serotonintransporters 5-HTTLPR I/D, and SLC6A4 rs16965628 polymorphisms in 80 OCD patients and 100 healthy controls was determined. Patients and controls were genotyped for COMT rs2097063 and SLC6A4 rs16965628 polymorphisms by real-time polymerase chain reaction (PCR). The 5-HTTLPR I/D polymorphism was genotyped using PCR and agarose gel electrophoresis. Severity of symptoms was checked with a Yale-Brown Obsession Compulsion Scale (Y-BOCS). When the OCD group and controls were compared, no significant difference was found between COMT -287A/G (rs2097063), 5-HTTLPR I/D polymorphisms, and OCD. However, a significant difference was found between 5-HTT rs16965628 polymorphism and OCD (p=0.025, OR=3.43, 95% CI 1.41-10.35). In addition, the G allele frequency was found to be higher for rs16965628 in the OCD group. No significant difference was observed between COMT -287A/G (rs2097063), SLC6A4 rs16965628, and 5-HTTLPR I/D polymorphisms and Y-BOCS scores (p>0.05). There was also lack of correlation between Yale-Brown scores and gender of OCD patients. On the other hand, combined genotypes of SLC6A4 rs16965628 GG+GC were found to be risk factors for OCD development (p=0.02, OR=3.464; 95% CI 1.214-9.883) in logistic regression analysis adjusted for age and gender. Our findings suggest that subjects carrying the G allele of rs16965628 have genetic susceptibility to OCD. These data are the first to suggest that polymorphism in serotonintransporter (rs16965628) is associated with the development of OCD in the Turkish population.

/NET selectivity are poorly understood. In this study, the structural basis for selectivity of the SERT selective inhibitor citalopram and the structurally closely related NET selective inhibitor talopram is delineated. A systematic structure-activity relationship study allowed identification of the substituents......, these findings provide important insight into the molecular basis for SERT/NET selectivity of antidepressants, which can be used to guide rational development of unique transporter inhibitors with fine-tuned transporter selectivity....

Premature ejaculation (PE) is a common ejaculatory complaint. The estimated rates among Turkish men reached 20%, although the severest type of PE (lifelong PE) usually does not exceed 2.3%. This could be seen in line with two survey studies involving five nations. They revealed that 2.5% of men had an intravaginal ejaculation latency time of ejaculation may be treated pharmacologically with a variety of different medications that act either centrally or locally to delay ejaculation and subsequent orgasm. Antidepressants, particularly members of the selective serotonin reuptake inhibitor class, retard ejaculation significantly. Recently, it was postulated that men with lifelong PE might result from a combination of polymorphisms of the serotonergic transporter and receptors, and other neurotransmitters and/or receptors. Our findings augment the significant effect of paroxetine in delaying ejaculation in the responders (P<0.001). Meanwhile, the findings do not suggest a positive association between such response and serotonintransporter gene promoter polymorphism.

Depression and fatigue are frequent side effects of interferon-alpha (IFN-alpha) treatment, and there is compelling evidence that the inflammatory response system (including interleukin-6, IL-6) and the serotonergic system is important in the pathophysiology of such symptoms. Functional polymorphisms in the promoter region of the IL-6 gene (rs1800795) and serotonintransporter gene (5-HTTLPR) have been identified as regulating these systems. The present study aimed to determine if these polymorphisms were associated with the development of depression and fatigue during IFN-alpha and ribavirin treatment. Ninety-eight Caucasian patients receiving pegylated IFN-alpha and ribavirin treatment for chronic hepatitis C virus at King\\'s College Hospital, London, and Emory University Hospital, Atlanta, participated in this prospective cohort study. Symptoms of depression and fatigue were measured before treatment and at weeks 4, 8, 12 and 24 during treatment. The \\'low IL-6\\' synthesizing genotype (CC) was associated with significantly fewer symptoms of depression (effect size = 0.7 at week 24; F = 9.4, d.f. = 436, P = 0.002). The \\'high transcription\\' serotonintransporter (5-HTT) genotype (LL) was also associated with significantly fewer symptoms of depression, but with a much smaller effect (effect size = 0.2 at week 24; F = 4.5, d.f. = 436, P = 0.03). Neither polymorphisms were associated with symptoms of fatigue (IL-6: F = 1.2, d.f. = 430, P = 0.2; 5-HTT: F = 0.5, d.f. = 430, P = 0.5). The smaller effects of the 5-HTT polymorphism on depression may be explained by an interaction between the genes (F = 5.0, d.f. = 434, P = 0.02): the \\'protective\\' effect of the 5-HTTLPR polymorphism was evident only in the presence of the \\'low IL-6\\' genotype (F = 5.4, d.f. = 64, P = 0.02), not in the presence of the \\'high IL-6\\' genotype (F = 2.2, d.f. = 369, P = 0.1). The association between the IL-6 polymorphism and reduced risk of depressive symptoms confirms the role

Background Depression is common in the elderly. The role of genetic and environmental factors in modulating depressive symptoms is not clear. Methods We evaluated the influence of serotonintransporter gene polymorphisms and recent adverse life events on depressive symptoms in an elderly Italian population. We used data from “InveCe.Ab”, a population-based study of 1321 subjects aged 70–74 years. We used the 15-item Geriatric Depression Scale (GDS) to assess depressive symptoms–a GDS score ≥5 points (GDS≥5) indicated the presence of clinically relevant symptoms–and performed 5-HTTLPR and rs25531 genotyping to obtain the triallelic polymorphism of the serotonintransporter. We used the Geriatric Adverse Life Events Scale to measure adverse life events, and logistic regression models to evaluate the role of genotype and recent adverse life events in depressive symptoms, controlling for potential confounders and independent predictors. Results Two hundred subjects (15.76%) had a GDS≥5. The 5-HTTLPR triallelic polymorphism was significantly associated with GDS≥5. Only S′S′ carriers showed an increased risk of depressive symptoms (ORadj = 1.81, p = .022); one extra adverse life event increased this risk by 14% (p = .061) independently of genotype. Other factors significantly related to GDS≥5 were: female gender (ORadj = 2.49, p depression (ORadj = 4.73, p depressive symptoms by 57% (p = .005) only in the L′L′ carriers, while antidepressant intake was directly related to GDS≥5 in the L′S′ carriers (ORadj = 2.46, p = .036) and borderline significant in the S′S′ carriers (ORadj = 2.41, p = .081). Discussion The S′S′ genotype and recent exposure to adverse life events were independently associated with depressive symptoms. The S′S′ genotype, compared with the environment, exerted a predominant effect on depressive symptoms, suggesting that it reduces the efficacy of antidepressant therapy. We conclude that genetics may be an

The combinatory effect of polymorphisms in serotonintransporter and monoamine oxidase-A genes on the aetiopathogenesis of alcoholism was investigated in a sample of 714 individuals. Increased frequency of subjects having three 'suspected' genotypes (5-HTTLPR-LL, STin2-1010 and MAO-A 3-repeat allele) was found among type-2 alcoholic patients (P=0.0189). Results highlight serotonergic/genetic contribution to early-onset alcoholism.

Several studies have been conducted to analyze the role of short polymorphism of serotonintransporter (5-HTTLPR) in response to psy-chosocial stress mediated by cortisol, having found inconsistent results. In order to synthesize and analyze available information about the role of short polymorphisms of 5-HTTLPR gen in the stress response, this meta-analysis has been carried out. A meta-analysis of studies published until November 2011 without language restrictions, which analyzed the effect ...

Previous studies have suggested that the serotonintransporter (5-HTT) gene and the gamma-aminobutyric acid receptor subunit beta3 (GABRB3) gene, or other genes in the 15q11-q13 region, are possibly involved in susceptibility to autism. To test this hypothesis we performed an association study...... and the GABRB3 genes are unlikely to play a major role in the aetiology of autism in our family data set....

Aims: Definition of the regional pattern of dopamine transporter (DAT) dysfunction in advanced Parkinson's disease (PD) and evaluation of a potential correlation between DAT binding and symptoms; elucidation of the role of DAT imaging in the differential diagnosis of PD and multiple system atrophy (MSA); assessment and comparison of serotonintransporter (SERT) binding in PD and MSA. Methods: [{sup 123}I]β-CIT SPECT was performed in 14 patients with advanced PD, 10 with moderate MSA and 20 healthy persons. Specific to non-specific tracer binding ratios (V{sub 3}{sup ''}) were calculated via ROI analysis of uptake images at 4 h (SERT binding) and 24 h (DAT binding) p. i. Results: In PD bilateral reduction of striatal DAT binding (63-70%) was seen. The caudate ipsilateral to the clinically predominantly affected side showed relatively the least impairment. Significant correlations (r = -0.54 to -0.64) between DAT binding and Hoehn and Yahr stage, UPDRS-scores and duration of disease were found. In MSA DAT binding was less reduced (40-48%) targeting the putamen contralateral to the side of clinical predominance. Significantly lower SERT binding was observed in PD midbrain and MSA hypothalamus compared to controls - and in MSA relative to PD mesial frontal cortex. Conclusions: In advanced PD striatal DAT binding is markedly reduced with the least reduction in caudate ipsilateral to the clinically predominantly affected side. In moderate MSA with asymmetrical symptoms DAT dysfunction is predominant in the contralateral putamen, a pattern seen in early PD. The reduction of SERT in the midbrain area of PD patients suggests additional tegmental degeneration while in MSA the serotonergic system seems to be more generally affected. (orig.)

A dual inhibitor of acetylcholinesterase (AChE) and serotonintransporter (SERT), RS-1259 (4-[1S)-methylamino-3-(4-nitrophenoxy)]propylphenyl N,N-dimethylcarbamate (fumaric acid)(1/2)salt), was newly synthesized. RS-1259 simultaneously inhibited AChE and SERT in the brain following an oral administration in mice and rats. Actual simultaneous elevation of extracellular levels of 5-HT and ACh in the rat hippocampus was confirmed by microdialysis. The compound was as effective as SERT inhibitors such as fluoxetine and fluvoxamine in a 5-hydroxytryptophan-enhancing test in mice. Spatial memory deficits in the two-platform task of a water maze in aged rats were ameliorated by RS-1259 as well as donepezil. Both RS-1259 and donepezil increased the awake episodes in the daytime electroencephalogram of rats. Although RS-1259 was weaker than donepezil in enhancing central cholinergic transmission, as observed by ACh elevation in the hippocampus and memory enhancement in aged rats, the efficacy of RS-1259 on the consciousness level, which reflects the whole activity in the brain, was almost the same as that of donepezil. These results suggest that both cholinergic and serotonergic systems are involved in maintaining brain arousal and that a dual inhibitor of AChE and SERT may be useful for the treatment of cognitive disorders associated with reduced brain activity such as in Alzheimer's disease.

Full Text Available Gene-by-environment interaction (GxEs studies have gained popularity over the last decade, but the robustness of such observed interactions has been questioned. The current study contributes to this debate by replicating the only study on the interaction between the serotonintransporter gene (5-HTTLPR and perceived parental support on adolescents' peer-related loneliness. A total of 1,111 adolescents (51% boys with an average age of 13.70 years (SD = 0.93 participated and three annual waves of data were collected. At baseline, adolescent-reported parental support and peer-related loneliness were assessed and genetic information was collected. Assessment of peer-related loneliness was repeated at Waves 2 and 3. Using a cohort-sequential design, a Latent Growth Curve Model was estimated. Overall, a slight increase of loneliness over time was found. However, the development of loneliness over time was found to be different for boys and girls: girls' levels of loneliness increased over time, whereas boys' levels of loneliness decreased. Parental support was inversely related to baseline levels of loneliness, but unrelated to change of loneliness over time. We were unable to replicate the main effect of 5-HTTLPR or the 5-HTTLPR x Support interaction effect. In the Discussion, we examine the implications of our non-replication.

Retrieval of congeneric and consistent SAR data sets for protein targets of interest is still a laborious task to do if no appropriate in-house data set is available. However, combining integrated open data sources (such as the Open PHACTS Discovery Platform) with workflow tools now offers the possibility of querying across multiple domains and tailoring the search to the given research question. Starting from two phylogenetically related protein targets of interest (the human serotonin and dopamine transporters), the whole chemical compound space was explored by implementing a scaffold-based clustering of compounds possessing biological measurements for both targets. In addition, potential hERG blocking liabilities were included. The workflow allowed studying the selectivity trends of scaffold series, identifying potentially harmful compound series, and performing SAR, docking studies and molecular dynamics (MD) simulations for a consistent data set of 56 cathinones. This delivered useful insights into driving determinants for hDAT selectivity over hSERT. With respect to the scaffold-based analyses it should be noted that the cathinone data set could be retrieved only when Murcko scaffold analyses were combined with similarity searches such as a common substructure search.

Full Text Available Scanpaths (the succession of fixations and saccades during spontaneous viewing contain information about the image but also about the viewer. To determine the viewer-dependent factors in the scanpaths of monkeys, we trained three adult males (Macaca mulatta to look for 3 s at images of conspecific facial expressions with either direct or averted gaze. The subjects showed significant differences on four basic scanpath parameters (number of fixations, fixation duration, saccade length, and total scanpath length when viewing the same facial expression/gaze direction combinations. Furthermore, we found differences between monkeys in feature preference and in the temporal order in which features were visited on different facial expressions. Overall, the between-subject variability was larger than the within- subject variability, suggesting that scanpaths reflect individual preferences in allocating visual attention to various features in aggressive, neutral, and appeasing facial expressions. Individual scanpath characteristics were brought into register with the genotype for the serotonintransporter regulatory gene (5-HTTLPR and with behavioral characteristics such as expression of anticipatory anxiety and impulsiveness/hesitation in approaching food in the presence of a potentially dangerous object.

[(11)C]AFM, or [(11)C]2-[2-(dimethylaminomethyl)phenylthio]-5-fluoromethylphenylamine, is a new positron emission tomography (PET) radioligand with high affinity and selectivity for the serotonintransporter (SERT). The purpose of this study was to determine the most appropriate kinetic model to quantify [(11)C]AFM binding in the healthy human brain. Positron emission tomography data and arterial input functions were acquired from 10 subjects. Compartmental modeling and the multilinear analysis-1(MA1) method were tested using the arterial input functions. The one-tissue model showed a lack of fit in low-binding regions, and the two-tissue model failed to estimate parameters reliably. Regional time-activity curves were well described by MA1. The rank order of [(11)C]AFM binding potential (BPND) matched well with the known regional SERT densities. For routine use of [(11)C]AFM, several noninvasive methods for quantification of regional binding were evaluated, including simplified reference tissue models (SRTM and SRTM2), and multilinear reference tissue models (MRTM and MRTM2). The best methods for region of interest (ROI) analysis were MA1, MRTM2, and SRTM2, with fixed population kinetic values ( or b') for the reference methods. The MA1 and MRTM2 methods were best for parametric imaging. These results showed that [(11)C]AFM is a suitable PET radioligand to image and quantify SERT in humans.

[(11)C]MADAM, or [(11)C]N,N-dimethyl-2-(2-amino-4-methylphenyl thio)benzylamine, is a radioligand suitable for positron emission tomography (PET) studies of the serotonintransporter (5-HTT) in man. The purpose of this study was to examine the test-retest reproducibility using a design tailored for future applied studies. Nine healthy male subjects were examined with PET and [(11)C]MADAM under baseline conditions at two occasions 4-8 weeks apart. The subjects participated in a Phase 1 trial to which the present study was an addendum. Eight regions of interest were studied, including frontal cortex, hippocampal complex, and the raphe nuclei. All regions, but the raphe nuclei, were defined on MR-images to which the PET-images were coregistered using SPM2. Binding potentials were calculated using the simplified reference tissue model, with cerebellum as reference region. Test-retest data were calculated from the binding potentials, and included binding potential (BP) quotient, BP difference, and the intraclass correlation coefficient. The quotient was about one in all regions, and the mean difference varied between 0 and 11%. The intraclass correlation coefficient varied between 0.96 and 0.51 in the raphe nuclei and averaged bilateral regions. [(11)C]MADAM was shown to have good to excellent reliability in measurements of 5-HTT binding in brain regions of interest in research on psychiatric disorders.

Gene-environment interactions that moderate aggressive behavior have been identified independently in the serotonintransporter (5-HTT) gene and monoamine oxidase A gene (MAOA). The aim of the present study was to investigate epistasis interactions between MAOA-variable number tandem repeat (VNTR), 5-HTTlinked polymorphism (LPR) and child abuse and the effects of these on aggressive tendencies in a group of otherwise healthy adolescents. A group of 546 Chinese male adolescents completed the Child Trauma Questionnaire and Youth self-report of the Child Behavior Checklist. Buccal cells were collected for DNA analysis. The effects of childhood abuse, MAOA-VNTR, 5-HTTLPR genotypes and their interactive gene-gene-environmental effects on aggressive behavior were analyzed using a linear regression model. The effect of child maltreatment was significant, and a three-way interaction among MAOA-VNTR, 5-HTTLPR and sexual abuse (SA) relating to aggressive behaviors was identified. Chinese male adolescents with high expression of the MAOA-VNTR allele and 5-HTTLPR “SS” genotype exhibited the highest aggression tendencies with an increase in SA during childhood. The findings reported support aggression being a complex behavior involving the synergistic effects of gene-gene-environment interactions. PMID:28203149

Full Text Available Transmitter exocytosis from the neuronal soma is evoked by brief trains of high frequency electrical activity and continues for several minutes. Here we studied how active vesicle transport towards the plasma membrane contributes to this slow phenomenon in serotonergic leech Retzius neurons, by combining electron microscopy, the kinetics of exocytosis obtained from FM1-43 dye fluorescence as vesicles fuse with the plasma membrane, and a diffusion equation incorporating the forces of local confinement and molecular motors. Electron micrographs of neurons at rest or after stimulation with 1 Hz trains showed cytoplasmic clusters of dense core vesicles at 1.5±0.2 and 3.7±0.3 µm distances from the plasma membrane, to which they were bound through microtubule bundles. By contrast, after 20 Hz stimulation vesicle clusters were apposed to the plasma membrane, suggesting that transport was induced by electrical stimulation. Consistently, 20 Hz stimulation of cultured neurons induced spotted FM1-43 fluorescence increases with one or two slow sigmoidal kinetics, suggesting exocytosis from an equal number of vesicle clusters. These fluorescence increases were prevented by colchicine, which suggested microtubule-dependent vesicle transport. Model fitting to the fluorescence kinetics predicted that 52-951 vesicles/cluster were transported along 0.60-6.18 µm distances at average 11-95 nms(-1 velocities. The ATP cost per vesicle fused (0.4-72.0, calculated from the ratio of the ΔG(process/ΔG(ATP, depended on the ratio of the traveling velocity and the number of vesicles in the cluster. Interestingly, the distance-dependence of the ATP cost per vesicle was bistable, with low energy values at 1.4 and 3.3 µm, similar to the average resting distances of the vesicle clusters, and a high energy barrier at 1.6-2.0 µm. Our study confirms that active vesicle transport is an intermediate step for somatic serotonin exocytosis by Retzius neurons and provides a

Transmitter exocytosis from the neuronal soma is evoked by brief trains of high frequency electrical activity and continues for several minutes. Here we studied how active vesicle transport towards the plasma membrane contributes to this slow phenomenon in serotonergic leech Retzius neurons, by combining electron microscopy, the kinetics of exocytosis obtained from FM1-43 dye fluorescence as vesicles fuse with the plasma membrane, and a diffusion equation incorporating the forces of local confinement and molecular motors. Electron micrographs of neurons at rest or after stimulation with 1 Hz trains showed cytoplasmic clusters of dense core vesicles at 1.5±0.2 and 3.7±0.3 µm distances from the plasma membrane, to which they were bound through microtubule bundles. By contrast, after 20 Hz stimulation vesicle clusters were apposed to the plasma membrane, suggesting that transport was induced by electrical stimulation. Consistently, 20 Hz stimulation of cultured neurons induced spotted FM1-43 fluorescence increases with one or two slow sigmoidal kinetics, suggesting exocytosis from an equal number of vesicle clusters. These fluorescence increases were prevented by colchicine, which suggested microtubule-dependent vesicle transport. Model fitting to the fluorescence kinetics predicted that 52-951 vesicles/cluster were transported along 0.60-6.18 µm distances at average 11-95 nms(-1) velocities. The ATP cost per vesicle fused (0.4-72.0), calculated from the ratio of the ΔG(process)/ΔG(ATP), depended on the ratio of the traveling velocity and the number of vesicles in the cluster. Interestingly, the distance-dependence of the ATP cost per vesicle was bistable, with low energy values at 1.4 and 3.3 µm, similar to the average resting distances of the vesicle clusters, and a high energy barrier at 1.6-2.0 µm. Our study confirms that active vesicle transport is an intermediate step for somatic serotonin exocytosis by Retzius neurons and provides a quantitative method

Background: A novel radioiodine ligand [{sup 123}I] ADAM (2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine) has been suggested as a promising serotonintransporter (SERT) imaging agent for the central nervous system. In this study, the biodistribution of SERTs in the rabbit brain was investigated using [{sup 123}I] ADAM and mapping images of the same animal produced by both single-photon emission computed tomography (SPECT) and microautoradiography. A semiquantification method was adopted to deduce the optimum time for SPECT imaging, whereas the input for a simple fully quantitative tracer kinetic model was provided from arterial blood sampling data. Methods: SPECT imaging was performed on female rabbits postinjection of 185 MBq [{sup 123}I] ADAM. The time-activity curve obtained from the SPECT images was used to quantify the SERTs, for which the binding potential was calculated from the kinetic modeling of [{sup 123}I] ADAM. The kinetic data were analyzed by the nonlinear least squares method. The effects of the selective serotonin reuptake inhibitors fluoxetine and p-chloroamphetamine (PCA) on rabbits were also evaluated. After scanning, the same animal was sacrificed and the brain was removed for microautoradiography. Regions-of-interest were analyzed using both SPECT and microautoradiography images. The SPECT images were coregistered manually with the corresponding microautoradiography images for comparative study. Results: During the time interval 90-100 min postinjection, the peak specific binding levels in different brain regions were compared and the brain stem was shown to have the highest activity. The target-to-background ratio was 1.89{+-}0.02. Similar studies with fluoxetine and PCA showed a background level for SERT occupation. Microautoradiography demonstrated a higher level of anatomical details of the [{sup 123}I] ADAM distribution than that obtained by SPECT imaging of the rabbit brain. Conclusion: SPECT imaging of the rabbit brain with

Epidemiological studies have revealed a strong genetic contribution to the risk for depression. Both reduced hippocampal serotonin neurotransmission and brain-derived neurotrophic factor (BDNF) levels have been associated with increased depression vulnerability and are also regulated during aging...... density. Hippocampal BDNF protein levels were measured by ELISA. An exacerbated age-related loss of serotonin fiber density specific for the CA1 area was observed in the cLH animals, whereas reduced hippocampal BDNF levels were seen in young and old cLH when compared with age-matched cNLH controls....... These observations indicate that aging should be taken into account when studying the neurobiological factors behind the vulnerability for depression and that understanding the effect of aging on genetically predisposed individuals may contribute to a better understanding of the pathophysiology behind depression...

Posttraumatic stress disorder (PTSD) is a prevalent, disabling anxiety disorder marked by behavioral and physiologic alterations which commonly follows a chronic course. Exposure to a traumatic event constitutes a necessary, but not sufficient, factor. There is evidence from twin studies supporting a significant genetic predisposition to PTSD. However, the precise genetic loci still remain unclear. The objective of the present study was to identify, in a case-control study, whether the brain-derived neurotrophic factor (BDNF) val66met polymorphism (rs6265), the dopamine transporter (DAT1) three prime untranslated region (3'UTR) variable number of tandem repeats (VNTR), and the serotonintransporter (5-HTTPRL) short/long variants are associated with the development of PTSD in a group of victims of urban violence. All polymorphisms were genotyped in 65 PTSD patients as well as in 34 victims of violence without PTSD and in a community control group (n = 335). We did not find a statistical significant difference between the BDNF val66met and 5-HTTPRL polymorphism and the traumatic phenotype. However, a statistical association was found between DAT1 3'UTR VNTR nine repeats and PTSD (OR = 1.82; 95% CI, 1.20-2.76). This preliminary result confirms previous reports supporting a susceptibility role for allele 9 and PTSD.

are important drug targets in treating i.e. affective disorders such as depression and anxiety, and for drugs of abuse such as ecstasy and cocaine. The normal function of the SERT relies on large conformational changes and its inhibition by antidepressants represents a conformational lock. Understanding...... the molecular mechanism of inhibition and which structural elements are involved in inhibitor binding and conformational changes of the transporter will provide clues for the development of improved drugs for the treatment of depression. Guided by our previous studies, we combined different biochemical methods......-HT transport. We also find that the potency of antidepressants is improved by in SERT with a lengthened IL5. These findings support the notion that intracellular loops are important substructures with a role in both the transport mechanism and molecular pharmacology of SERT....

Radiolabelled 2{beta}-carbomethoxy-3{beta}-(4-iodophenyl)tropane ({beta}-CIT) has been used in clinical studies for the imaging of dopamine and serotonintransporters with single-photon emission tomography (SPET). 2{beta}-Carbomethoxy-3{beta}-(4-iodophenyl)nortropane (nor-{beta}-CIT) is a des-methyl analogue of {beta}-CIT, which in vitro has tenfold higher affinity (IC{sub 50}=0.36 nM) to the serotonintransporter than {beta}-CIT (IC{sub 50}=4.2 nM). Nor-{beta}-CIT may thus be a useful radioligand for imaging of the serotonintransporter. In the present study iodine-125 and carbon-11 labelled nor-{beta}-CIT were prepared for in vitro autoradiographic studies on post-mortem human brain cryosections and for in vivo positron emission tomography (PET) studies in Cynomolgus monkeys. Whole hemisphere autoradiography with [{sup 125}I]nor-{beta}-CIT demonstrated high binding in the striatum, the thalamus and cortical regions of the human brain. Addition of a high concentration (1 {mu}M) of citalopram inhibited binding in the thalamus and the neocortex, but not in the striatum. In PET studies with [{sup 11}C]nor-{beta}-CIT there was rapid uptake of radioactivity in the monkey brain (6% of injected dose at 15 min) and high accumulation of radioactivity in the striatum, thalamus and neocortex. Thalamus to cerebellum and cortex to cerebellum ratios were 2.5 and 1.8 at 60 min, respectively. The ratios obtained with [{sup 11}C]nor-{beta}-CIT were 20%-40% higher than those previously obtained with [{sup 11}C]{beta}-CIT. Radioactivity in the thalamus and the neocortex but not in the striatum was displaceable with citalopram (5 mg/kg). In conclusion, nor-{beta}-CIT binds to the serotonintransporter in the primate brain in vitro and in vivo and has potential for PET and SPET imaging of the serotonintransporter in human brain. (orig.). With 4 figs.

Stimulation of serotonergic neurotransmission by psilocybin has been shown to shift emotional biases away from negative towards positive stimuli. We have recently shown that reduced amygdala activity during threat processing might underlie psilocybin's effect on emotional processing. However, it is still not known whether psilocybin modulates bottom-up or top-down connectivity within the visual-limbic-prefrontal network underlying threat processing. We therefore analyzed our previous fMRI data using dynamic causal modeling and used Bayesian model selection to infer how psilocybin modulated effective connectivity within the visual-limbic-prefrontal network during threat processing. First, both placebo and psilocybin data were best explained by a model in which threat affect modulated bidirectional connections between the primary visual cortex, amygdala, and lateral prefrontal cortex. Second, psilocybin decreased the threat-induced modulation of top-down connectivity from the amygdala to primary visual cortex, speaking to a neural mechanism that might underlie putative shifts towards positive affect states after psilocybin administration. These findings may have important implications for the treatment of mood and anxiety disorders.

Full Text Available Stimulation of serotonergic neurotransmission by psilocybin has been shown to shift emotional biases away from negative towards positive stimuli. We have recently shown that reduced amygdala activity during threat processing might underlie psilocybin's effect on emotional processing. However, it is still not known whether psilocybin modulates bottom-up or top-down connectivity within the visual-limbic-prefrontal network underlying threat processing. We therefore analyzed our previous fMRI data using dynamic causal modeling and used Bayesian model selection to infer how psilocybin modulated effective connectivity within the visual–limbic–prefrontal network during threat processing. First, both placebo and psilocybin data were best explained by a model in which threat affect modulated bidirectional connections between the primary visual cortex, amygdala, and lateral prefrontal cortex. Second, psilocybin decreased the threat-induced modulation of top-down connectivity from the amygdala to primary visual cortex, speaking to a neural mechanism that might underlie putative shifts towards positive affect states after psilocybin administration. These findings may have important implications for the treatment of mood and anxiety disorders.

/dephosphorylation during transporter regulation by multiple pathways. In particular, activation and/or inhibition of kinases including PKC, PKG, p38MAPK, and CaMKII modulate SERT function and trafficking. The molecular mechanisms by which kinase activity is linked to SERT regulation are poorly understood, including...... the identity of specific phosphorylated residues. To elucidate SERT phosphorylation sites, we have generated peptides corresponding to the entire intracellular region of human SERT and performed in vitro phosphorylation assays with a panel of kinases suggested to be involved in SERT regulation or for which...

In the current study, we investigated how individual variants in the serotonin promoter gene, previously associated with smoking cessation and linked to anxiety-related personality traits, were associated with individual differences in responsiveness to bupropion and cognitive behavioral therapy (CBT) in a clinical population. We hypothesize that subjects with the long allele may be less responsive to treatment. Altogether 61 schizophrenic patients (46 M, 15 F) on stable neuroleptic medication were initially enrolled in a smoking reduction program (prospective, double-blind, placebo-controlled) including cognitive behavioral therapy plus placebo or CBT plus bupropion. Additionally, subjects were genotyped for a polymorphism in the serotonintransporter (SLC6A4). Thirty-two subjects (23 M, 9 F) completed a 14-week course of treatment. While both groups of subjects demonstrated significant reductions in smoking behavior due to CBT, subjects receiving bupropion did not show significant differences in smoking behavior when compared to placebo. In addition, analysis by SPSS repeated measures multivariate showed a significant sex by SLC6A4 genotype interaction on the number of cigarettes smoked. Only male subjects with at least one short promoter region allele (short/short and short/long combined) showed a reduction in cigarette consumption as a result of treatment. This study provides preliminary evidence of how polymorphisms in the serotonintransporter can be informative in predicting individual responses to smoking reduction therapy.

Full Text Available Vitamin D3 has been described to have different extraskeletal roles by acting as parahormone in obesity, diabetes, cancer, cognitive impairment, and dementia and to have important regulatory functions in innate immunity. There are no studies showing extraskeletal changes associated with hypovitaminosis D3 in eating disorders. Methods. We have analyzed the blood of 18 patients affected by anorexia nervosa and bulimia nervosa collected over a 15-month period. We performed a panel of chemical and clinical analyses: the assay of vitamin D3, the immunoblotting of vitamin D receptor and peroxisome proliferator-activated receptor gamma, and the genotyping of 5-hydroxytryptamine transporter linked polymorphic region. Results. We choose 18 patients with a normal blood test profile such as thyroid hormones, hepatic and renal parameters, triglycerides, proteins, vitamin B12, and folic acid. Among these emerged the case of a woman with long-term anorexia nervosa and the case of a woman with long-term bulimia nervosa both complicated by anxiety and depression, severe hypovitaminosis D3, decrease of vitamin D receptor, leukopenia, and 5-hydroxytryptamine transporter linked polymorphic region short allele. Conclusion. The results induce hypothesising that the severe hypovitaminosis D3 might be responsible for the lack of the inflammatory response and the depressive symptoms in patients with long-term eating disorders.

Vitamin D3 has been described to have different extraskeletal roles by acting as parahormone in obesity, diabetes, cancer, cognitive impairment, and dementia and to have important regulatory functions in innate immunity. There are no studies showing extraskeletal changes associated with hypovitaminosis D3 in eating disorders. Methods. We have analyzed the blood of 18 patients affected by anorexia nervosa and bulimia nervosa collected over a 15-month period. We performed a panel of chemical and clinical analyses: the assay of vitamin D3, the immunoblotting of vitamin D receptor and peroxisome proliferator-activated receptor gamma, and the genotyping of 5-hydroxytryptamine transporter linked polymorphic region. Results. We choose 18 patients with a normal blood test profile such as thyroid hormones, hepatic and renal parameters, triglycerides, proteins, vitamin B12, and folic acid. Among these emerged the case of a woman with long-term anorexia nervosa and the case of a woman with long-term bulimia nervosa both complicated by anxiety and depression, severe hypovitaminosis D3, decrease of vitamin D receptor, leukopenia, and 5-hydroxytryptamine transporter linked polymorphic region short allele. Conclusion. The results induce hypothesising that the severe hypovitaminosis D3 might be responsible for the lack of the inflammatory response and the depressive symptoms in patients with long-term eating disorders.

Recent studies have proposed an interrelation between the brain-derived neurotrophic factor (BDNF) val66met polymorphism and the serotonin system. In this study, we investigated whether the BDNF val66met polymorphism or blood BDNF levels are associated with cerebral 5-hydroxytryptamine 2A (5-HT(2A......)) receptor or serotonintransporter (SERT) binding in healthy subjects. No statistically significant differences in 5-HT(2A) receptor or SERT binding were found between the val/val and met carriers, nor were blood BDNF values associated with SERT binding or 5-HT(2A) receptor binding. In conclusion, val66met...... BDNF polymorphism status is not associated with changes in the serotonergic system. Moreover, BDNF levels in blood do not correlate with either 5-HT(2A) or SERT binding....

Pulmonary arterial hypertension is a common disease with sustained elevation in pulmonary artery pressure, and irreversible pulmonary artery remodeling.As a kind of vasoactive substance,serotonin(5-HT)promotes smooth muscle cell proliferation and configuration reconstitution in pulmonary artery by serotonintransporter(SERT).So, it is meaningful to investigate the roles of 5-HT and SERT in the development of pulmonary arterial hypertension, and discuss the possibility of 5-HT/SERT to be a novel therapeutic approach for pulmonary arterial hypertension.%肺动脉高压是临床常见的以肺血管阻力进行性增加并伴有不可逆的血管构型重塑为特征的疾病.5-羟色胺作为一种血管活性物质,可以通过5-羟色胺转运体介导,诱导肺动脉平滑肌细胞增殖,促进肺中小动脉构型重塑.因此,揭示5-羟色胺及5-羟色胺转运体在肺动脉高压形成发展中的重要作用,探讨其成为抗肺动脉高压药物治疗新靶点的可能性具有重要意义.

The serotonintransporter promoter polymorphism (5-HTTLPR) has been investigated regarding its association with neuroticism, which, in its turn, is a personality dimension often found in patients with panic disorder (PD). It has been recently evidenced that the long 5-HTTLPR polymorphism has a genetic variation (Lg), which is related to its lower expression. The objective of this study was to assess the association between the 5-HTTLPR polymorphism in the triallelic system and the neurotic personality traits in patients in PD remission. Sixty-seven Caucasian patients with PD diagnosis according to the DSM-IV-TR assessed with the MINI (mini international neuropsychiatric interview) were included. The MMPI (Minnesota multiphasic personality inventory) was used to assess the personality. The remission of PD symptoms was defined as CGI (clinical global impression)

Full Text Available Abstract Background Mental deficiency has been linked to abnormalities in cortical neuronal network connectivity and plasticity. These mechanisms are in part under the control of two interacting signalling pathways, the serotonergic and the brain-derived neurotrophic (BDNF pathways. The aim of the current paper is to determine whether particular alleles or genotypes of two crucial genes of these systems, the serotonintransporter gene (SLC6A4 and the brain-derived neurotrophic factor gene (BDNF, are associated with mental deficiency (MD. Methods We analyzed four functional polymorphisms (rs25531, 5-HTTLPR, VNTR, rs3813034 of the SLC6A4 gene and one functional polymorphism (Val66 Met of the BDNF gene in 98 patients with non-syndromic mental deficiency (NS-MD and in an ethnically matched control population of 251 individuals. Results We found no significant differences in allele and genotype frequencies in the five polymorphisms studied in the SLC6A4 and BDNF genes of NS-MD patients versus control patients. While the comparison of the patterns of linkage disequilibrium (D' in the control and NS-MD populations revealed a degree of variability it did not, however, reach significance. No significant differences in frequencies of haplotypes and genotypes for VNTR/rs3813034 and rs25531/5-HTTLPR were observed. Conclusion Altogether, results from the present study do not support a role for any of the five functional polymorphisms of SLC6A4 and BDNF genes in the aetiology of NS-RM. Moreover, they suggest no epistatic interaction in NS-MD between polymorphisms in BDNF and SLC6A4. However, we suggest that further studies on these two pathways in NS-MD remain necessary.

Full Text Available Studies of populations at genetic risk have the potential to explore the underlying structural and functional mechanisms in the development of psychological disorders. The polymorphic region (5-HTTLPR in the serotonintransporter gene (SLC6A4 has been associated with major depression (Caspi et al., 2003. In healthy women, variation in the human brain white matter microstructure integrity in the uncinate fascicule (UF has been suggested as an endophenotypes in the development of major depression (MDD. Pacheco et al. (2009 found a unique effect of age and 5-HTTLPR within the left frontal UF. The present study examined whether these associations persist along the adult life span. Thirty-seven right-handed healthy women between 21 and 61 years of age were invited for a diffusion MRI study. The functional polymorphism 5-HTTLPR located in the promoter region of the SLC6A4 gene was genotyped using polymerase chain reaction (PCR. Fractional anisotropy (FA was generated for the UF based on Tract-Based Spatial Statistics (TBSS. Models of emotion regulation circuitry suggest that working memory is important in conscious emotion regulation (Price and Drevets, 2010. To explore if 5-HTTLPR is related to this aspects of emotion processing, a working memory pathway, the superior longitudinal fascicule (SLF was included. The results demonstrate that age may explain the hypothesized association between 5-HTTLPR and frontal uncinate fascicule white matter integrity in healthy adult women. Both white matter changes associated with the aging process and those associated with growth and development may explain why the earlier reported unique effects of genotype in frontal UF FA do not persist into adulthood.

Efficacy of antidepressant drugs is often limited. One of the limiting factors may be diet. This study shows that the effect of escitalopram in the forced swimming test is diminished in rats by food restriction that decreased body weight by 8%. The primary target for escitalopram is the serotonin (5-HT) transporter. Using high-speed chronoamperometry to measure 5-HT clearance in vivo in rats fed the same food-restricted diet, the rate of 5-HT clearance from extracellular fluid in brain was dramatically increased. Increased 5-HT transporter function under conditions of dietary restriction might contribute to the decreased effect of escitalopram. These results suggest that diet plays an integral role in determining efficacy of antidepressant drugs, and might well generalize to other psychoactive drugs that impinge upon the 5-HT transporter.

The Chediak-Higashi syndrome is characterized by a serotonin platelet defect and neuronal dysfunction. Whole blood serotonin concentration, serotonin brain concentration, and synaptosomal uptake of serotonin were determined in mice with the syndrome. While brain serotonin uptake in the affected mice was not significantly different from that in nonaffected mice, whole blood serotonin concentration was markedly reduced. These data suggest that in human neuropathies with platelet serotonin defect, a parallel neuronal serotonin disorder may not be assumed.

Full Text Available Objective and Methods. Although the interaction between fatigue and depression in patients with chronic hepatitis C infection (HCV has been recognized, the biological correlates of this observation have yet to be reported. We addressed this issue by examining serotonintransporter- (SERT- driven [14C]-serotonin uptake rate (SUR and serotonin content in platelets of 65 untreated HCV patients and 65 healthy control subjects (HCS. All patients completed report questionnaires for fatigue, depression, and general psychopathology. Structured interviews were conducted by a board-certified psychiatrist. Results. Whereas 36 of the patients experienced fatigue of moderate-to-severe intensity, only 16 reported symptoms of depression (BDI score > 10. Mean SUR in patients with depressive symptoms was significantly higher relative to the HCS, corresponding to a large Cohen’s effect size of d=1.45 (95% CI=0.66—1.83. Patients who rated their fatigue to have a marked impact on mood and activity displayed a moderate relationship between the BDI score and SUR (n=18, r=0.563, P=0.015, which becomes stronger after controlling for age, gender, and thrombocytopenia (rpart=0.710, P=0.003. In the univariate analysis, high fatigue interference score, thrombocytopenia, and high SUR were all significant predictors of depression. Conclusions. High SERT activity could be implicated in the expression of depressive symptoms especially in a subgroup of HCV patients who are feeling fatigue as markedly distressing.

The serotonintransporter-linked promoter region polymorphism (5-HTTLPR) is thought to be associated with some serotonin dysfunction-related psychopathologies such as depression and anxiety disorders. Suicide and suicide-related behaviors such as violence, aggression, and impulsivity have been reproducibly associated with serotonin dysfunction and are partially genetic. This study examined the association of 5-HTTLPR with suicidal behavior and related traits in Israeli suicidal adolescent inpatients using the haplotype relative risk (HRR) method that controls for artifacts caused by population stratification. Forty-eight inpatient adolescents who recently attempted suicide were assessed by structured interviews for detailed clinical history, diagnoses, suicide intent, suicide risk, impulsivity, violence, and depression. Blood samples were collected and DNA extracted from patients and their biological parents. The 5-HTTLPR allele frequencies were tested for association with suicidality by the HRR method. In addition, the relationship between genotypes and phenotypic severity of several clinical parameters was analyzed. No significant allelic association of the 5-HTTLPR polymorphism with suicidal behavior was found (chi square = 0.023; P = 0.88). Analysis of variance of the suicide-related trait measures for the three genotypes demonstrated a significant difference in violence measures between patients carrying the LL and LS genotypes (9.50+/-4.04 vs. 5.36+/-4.03; P = 0.029). This study suggests that the 5-HTTLPR polymorphism is unlikely to have major relevance to the pathogenesis of suicidal behavior in adolescence but may contribute to violent behavior in this population.

Depression is a major health issue, which is routinely treated with selective serotonin reuptake inhibitors. However, although these agents display a favorable effect on mood, they often fail to improve conditions that accompany depression including cognitive impairment and fatigue. In pre-clinical studies histamine H(3) receptor antagonists have demonstrated both pro-cognitive and wake-promoting effects suggesting that the combination of a histamine H(3) receptor antagonist and a serotonin reuptake inhibitor may have utility as an antidepressant therapy. To this end we sought to introduce histamine H(3) receptor antagonist activity into both known selective serotonin reuptake inhibitors and novel templates. These efforts have afforded several series of compounds with the desired activities. Selected examples demonstrated in vivo efficacy both in pre-clinical models of depression and wakefulness.

Depression is a common mental illness and a leading cause of disability. The most widely prescribed antidepressant medications are serotonin (5-HT) selective reuptake inhibitors (SSRIs). Although there is much support for 5-HT transporter (SERT) antagonism as a basis of antidepressant efficacy, this evidence is indirect and other targets and mechanisms have been proposed. In order to distinguish SERT-dependent and -independent effects of SSRIs, we developed a knock-in mouse model whereby high-affinity interactions of many antidepressants at SERT have been ablated via knock-in substitution (SERT Met172) without disrupting 5-HT recognition or uptake. Here we utilize the C57BL/6J SERT Met172 model to evaluate SERT dependence for the actions of two widely prescribed SSRIs, fluoxetine and citalopram, in tests sensitive to acute and chronic actions of antidepressants. In the tail suspension and forced swim tests, fluoxetine and citalopram fail to reduce immobility in SERT Met172 mice. In addition, SERT Met172 mice are insensitive to chronic fluoxetine and citalopram administration in the novelty induced hypophagia test (NIH) and fail to exhibit enhanced proliferation or survival of hippocampal stem cells. In both acute and chronic studies, SERT Met172 mice maintained sensitivity to paroxetine, an antidepressant that is unaffected by the Met172 mutation. Together, these studies provide definitive support for an essential role of SERT antagonism in the acute and chronic actions of two commonly used SSRIs in these tests, and reinforce the utility of the SERT Met172 model for isolating SERT/5-HT contributions of drug actions in vivo.

In the present study, we used high-speed chronoamperometry to examine serotonin (5-HT) transporter (5-HTT) function in vivo in 2-, 5-, and 10-month-old brain-derived neurotrophic factor (BDNF)+/- mice. The rate of clearance of exogenously applied 5-HT was measured in CA3 region of hippocampus. In 2-month-old mice, the rate of 5-HT clearance did not differ between BDNF+/+ and BDNF+/- mice. In BDNF+/+ mice, 5-HT clearance rate (Tc) increased markedly with age. In contrast, Tc remained relatively static in BDNF+/- mice across 2-, 5-, and 10-month age groups. At 5 months of age, female BDNF+/+ mice had a lower maximal velocity (Vmax) for 5-HT clearance than male BDNF+/+ mice. There was a similar trend in 5-month-old BDNF+/- mice, but this did not reach statistical significance. There was an age-dependent increase in KT value for 5-HT clearance (i.e., decreased in vivo affinity of 5-HTT), but no significant effect of genotype or gender. 5-HTT density, as measured by [3H]cyanoimipramine binding, was not different between BDNF+/+ and BDNF+/- mice, although there was a significant increase in 5-HTT binding with age. The selective 5-HT reuptake inhibitor fluvoxamine (50 and 100 pmol) significantly decreased 5-HT clearance in BDNF+/+ mice, but not in BDNF+/- mice. Our data suggest that the profoundly reduced ability of 5- and 10-month-old BDNF+/- mice to clear 5-HT is not because of a decrease in the total number of 5-HTTs, but may be due to functional deficits in the 5-HTT, e.g., in the machinery/signaling required for insertion of 5-HTTs into the plasma membrane and/or activation of the 5-HTT once it is positioned to take up 5-HT from extracellular fluid.

Full Text Available We aimed to find out if the serotonin receptor (HT102T>C and serotonintransporter (STin 2 polymorphisms play any role in genetic susceptibility of migraine. For the study, 217 migraine patients and 217 healthy controls (HC were recruited and genotyping was carried out using the Polymerase Chain Reaction and Restriction Fragment Length polymorphism (PCR-RFLP method. All results were Bonferroni corrected. We could not find any significant differences in the genotype or allele frequencies in case of HT 102 T>C polymorphism between migraine patients and healthy controls (P value=0.224. No significant association was seen at allele and carrier levels. Sub-grouping the patients on the basis of gender or on basis of migraine type i.e. with or without aura also did not show any association. Similarly, no difference in genotype (P value=0.236, allele (P value=0.550 or carrier frequency (P value=0.771 in STin 2 VNTR polymorphism was observed between migraine patients. However, HT 102 TC genotype was observed to interact significantly with the STin 2.10/10 genotype in enhancing risk of migraine, both with and without aura. In conclusion, the HT102 T>C receptor and the STin 2 VNTR transporter polymorphisms, did not individually confer any significant risk of migraine or its clinical subtypes but the two polymorphisms appear to synergistically influence susceptibility to migraine. Serotonintransporter (STin2 VNTR and receptor (HT 102T>C polymorphisms; Migraine with aura (MA; Migraine without aura (MO; Genetic susceptibility

Mutations in the C terminus of the serotonintransporter (SERT) disrupt folding and export from the endoplasmic reticulum. Here we examined the hypothesis that a cytosolic heat shock protein relay was recruited to the C terminus to assist folding of SERT. This conjecture was verified by the following observations. (i) The proximal portion of the SERT C terminus conforms to a canonical binding site for DnaK/heat shock protein of 70 kDa (HSP70). A peptide covering this segment stimulated ATPase...

Two novel radioligands for the serotonintransporter (SERT), [I-125]{3-[5-iodo-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-1-yl]-propyl}-dimethylamine ([I-125]-2) and S-[I-125]{3-[5-iodo-1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-1-yl]-propyl}-dimethylamine ([I-125]-(S)-2) were synthesized in a ...... of the radioligand in imaging cortical SERT distribution in vivo. These data suggest that the iodine-labelled derivatives of citalopram and escitalopram are not superior to another SPECT tracer for the SERT, namely [I-123] ADAM....

Full Text Available Abstract Background A better understanding of the genetic determinants of tobacco smoking might help in developing more effective cessation therapies, tailored to smokers' genotype. Insertion/deletion polymorphism in the promoter region of the serotonintransporter gene (5-HTTLPR has been linked to vulnerability to smoking and ability to quit. We aimed to determine whether 5-HTTLPR genotype is associated with smoking behavior in Caucasians from Northern Poland and to investigate other risk factors for tobacco smoking. Methods 5-HTTLPR genotypes were determined in 149 ever smokers (66 females; mean age 53.0 years and 158 gender and ethnicity matched never smoking controls (79 females; mean age 45.0 years to evaluate the association of this polymorphism with ever smoking status. Analysis of smokers was performed to evaluate the role of 5-HTTLPR in the age of starting regular smoking, the number of cigarettes smoked daily, pack-years, FTND score, duration of smoking, and the mean length of the longest abstinence on quitting. Genotype was classified according to the presence or absence of the short (S allele vs. the long (L allele of 5-HTTLPR (i.e., S/S + S/L vs. L/L. Logistic regression analysis was also used to evaluate correlation between ever smoking and several selected variables. Results We found no significant differences in the rates of S allele carriers in ever smokers and never smokers, and no relationship was observed between any quantitative measures of smoking and the polymorphism. Multivariate analysis demonstrated significant association between the older age (OR = 4.03; 95% CI: 2.33–6.99 and alcohol dependence (OR = 10.23; 95% CI: 2.09–50.18 and smoking. Conclusion 5-HTTLPR seems to be not a major factor determining cigarette smoking in Poles. Probably, the risk of smoking results from a large number of genes, each contributing a small part of the overall risk, while numerous non-genetic factors might strongly influence these

The extraction of serotonin from the blood during transorgan passage through the heart was studied using Langendorff-perfused rabbit hearts. Outflow dilution curves of /sup 131/I- or /sup 125/I-labeled albumin, (/sup 14/C)sucrose, and (3H)serotonin injected simultaneously into the inflow were fitted with an axially distributed blood-tissue exchange model to examine the extraction process. The model fits of the albumin and sucrose outflow dilution curves were used to define flow heterogeneity, intravascular dispersion, capillary permeability, and the volume of the interstitial space, which reduced the degrees of freedom in fitting the model to the serotonin curves. Serotonin extractions, measured against albumin, during single transcapillary passage, ranged from 24 to 64%. The ratio of the capillary permeability-surface area products for serotonin and sucrose, based on the maximum instantaneous extraction, was 1.37 +/- 0.2 (n = 18), very close to the predicted value of 1.39, the ratio of free diffusion coefficients calculated from the molecular weights. This result shows that the observed uptake of serotonin can be accounted for solely on the basis of diffusion between endothelial cells into the interstitial space. Thus it appears that the permeability of the luminal surface of the endothelial cell is negligible in comparison to diffusion through the clefts between endothelial cells. In 18 sets of dilution curves, with and without receptor and transport blockers or competitors (ketanserin, desipramine, imipramine, serotonin), the extractions and estimates of the capillary permeability-surface area product were not reduced, nor were the volumes of distribution. The apparent absence of transporters and receptors in rabbit myocardial capillary endothelium contrasts with their known abundance in the pulmonary vasculature.

Recent progress in reducing turbulent transport in stellarators and tokamaks by 3D shaping using a stellarator optimization code in conjunction with a gyrokinetic code is presented. The original applications of the method focussed on ion temperature gradient transport in a quasi-axisymmetric stellarator design. Here, an examination of both other turbulence channels and other starting configurations is initiated. It is found that the designs evolved for transport from ion temperature gradient turbulence also display reducedtransport from other transport channels whose modes are also stabilized by improved curvature, such as electron temperature gradient and ballooning modes. The optimizer is also applied to evolving from a tokamak, finding appreciable turbulence reduction for these devices as well. From these studies, improved understanding is obtained of why the deformations found by the optimizer are beneficial, and these deformations are related to earlier theoretical work in both stellarators and tokamaks.

Full Text Available Duchenne muscular dystrophy (DMD is a recessive X-linked fatal disorder caused by a mutation in the dystrophin gene. Although several therapeutic approaches have been studied, none has led to substantial long-term effects in patients. The aim of this study was to test a serotonin and histamine (S&H combination on human skeletal myoblasts and Dmdmdx mice for its effects on muscle strength and injury. Normal human bioartificial muscles (BAMs were treated, and muscle tetanic forces and muscle injury tests were performed using the MyoForce Analysis System. Dmdmdx mice, the murine model of DMD, were administered serotonin, histamine, or S&H combination twice daily for 6 weeks, and functional performance tests were conducted once a week. The S&H combination treatment caused significant increases in tetanic forces at all time points and concentrations tested as compared to the saline controls. Dose response of the BAMs to the treatment demonstrated a significant increase in force generation at all concentrations compared to the controls after 3 to 4 days of drug treatment. The highest 3 concentrations had a significant effect on lowering contractile-induced injury as measured by a reduction in the release of adenylate kinase. Histamine-only and S&H treatments improved grip strength of Dmdmdx mice, whereas serotonin-only treatment resulted in no significant improvement in muscle strength. The results of this study indicate that S&H therapy might be a promising new strategy for muscular dystrophies and that the mechanism should be further investigated.

The serotonin syndrome is a hyperserotoninergic state resulting from an excess of intrasynaptic 5-hydroxytryptamine, induced by multiple psychotropic agents, but also non psychiatric drugs. It is a potentially dangerous and sometimes lethal condition. The clinical manifestations usually include cognitive, neuromuscular and autonomic features and are mediated by the action of serotonin on various subtypes of receptors. The main differential diagnosis is the neuroleptic malignant syndrome. Treatment is mainly supportive. No pharmacological agent has been definitely demonstrated really effective. However, reports of cases treated with the 5-HT2 blockers, including cyproheptadine or chlorpromazine have suggested that these agents could have some efficacy. Serotonin syndrome is a toxic condition which requires heightened clinical awareness among physicians in order to prevent, recognize, and treat the condition promptly.

The psychobiological model of personality by Cloninger and colleagues originally hypothesized that interindividual variability in the temperament dimension 'harm avoidance' (HA) is explained by differences in the activity of the brain serotonin system. We assessed brain serotonintransporter (5-HTT...

Bacopa monnieri (BM) has been used in Ayurvedic medicine as a nootropic, anxiolytic, antiepileptic and antidepressant. An n-butanol extract of the plant (nBt-ext BM) was analysed and found to contain Bacoside A (Bacoside A3, Bacopaside II and Bacopasaponin C). The effects of the BM extract were then studied on morphine-induced hyperactivity as well as dopamine and serotonin turnover in the striatum since these parameters have a role in opioid sensitivity and dependence. Mice were pretreated with saline or nBt-ext BM (5, 10 and 15 mg/kg, orally), 60 min before morphine administration and locomotor activity was subsequently recorded. Immediately after testing, striatal tissues were analysed for dopamine (DA), serotonin (5HT) and their metabolites using HPLC coupled with electrochemical detection. The results indicated that nBt-ext BM significantly (p < 0.001) decreased locomotor activity in both the saline and morphine treated groups. Additionally, nBt-ext BM significantly lowered morphine-induced dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindole acetic acid (5-H1AA) upsurges in the striatum but failed to affect DA, 5-HT and their metabolites in the saline treated group. These findings suggest that nBt-ext BM has an antidopaminergic/serotonergic effect and may have potential beneficial effects in the treatment of morphine dependence.

Diketopiperazines (DKPs) are naturally-occurring cyclic dipeptides with a small structure and are found in many organisms and in large amounts in some foods and beverages. We found that a chicken essence beverage, which is popular among Southeast Asians as a traditional remedy and a rich source of DKPs, inhibited the serotonintransporter (SERT) and suppressed serotonin uptake from rat brain synaptosomes, which prompted us to isolate and identify the active substance(s). We purified a SERT inhibitor from the chicken essence beverage and identified it as the DKP cyclo(L-Phe-L-Phe). Interestingly, it was a naturally occurring dual inhibitor that inhibited both SERT and acetylcholinesterase (AChE) in vitro. The DKP increased extracellular levels of the cerebral monoamines serotonin, norepinephrine, and dopamine in the medial prefrontal cortex and acetylcholine in the ventral hippocampus of freely moving rats when administered orally. Moreover, cyclo(L-Phe-L-Phe) significantly shortened escape latency in the water maze test in depressed mice previously subjected to a repeated open-space swimming task, which induces a depression-like state. Cyclo(L-Phe-L-Phe) also significantly improved accuracy rates in a radial maze test in rats and increased step-through latencies in a passive avoidance test in mice with scopolamine-induced amnesia. These animal test results suggest that cyclo(L-Phe-L-Phe), which is present abundantly in some foods such as chicken essence, may abrogate the onset of depression and, thus, contribute to preventing the development of Alzheimer's disease and other dementia, because senile depression is a risk factor for dementia.

Full Text Available Diketopiperazines (DKPs are naturally-occurring cyclic dipeptides with a small structure and are found in many organisms and in large amounts in some foods and beverages. We found that a chicken essence beverage, which is popular among Southeast Asians as a traditional remedy and a rich source of DKPs, inhibited the serotonintransporter (SERT and suppressed serotonin uptake from rat brain synaptosomes, which prompted us to isolate and identify the active substance(s. We purified a SERT inhibitor from the chicken essence beverage and identified it as the DKP cyclo(L-Phe-L-Phe. Interestingly, it was a naturally occurring dual inhibitor that inhibited both SERT and acetylcholinesterase (AChE in vitro. The DKP increased extracellular levels of the cerebral monoamines serotonin, norepinephrine, and dopamine in the medial prefrontal cortex and acetylcholine in the ventral hippocampus of freely moving rats when administered orally. Moreover, cyclo(L-Phe-L-Phe significantly shortened escape latency in the water maze test in depressed mice previously subjected to a repeated open-space swimming task, which induces a depression-like state. Cyclo(L-Phe-L-Phe also significantly improved accuracy rates in a radial maze test in rats and increased step-through latencies in a passive avoidance test in mice with scopolamine-induced amnesia. These animal test results suggest that cyclo(L-Phe-L-Phe, which is present abundantly in some foods such as chicken essence, may abrogate the onset of depression and, thus, contribute to preventing the development of Alzheimer's disease and other dementia, because senile depression is a risk factor for dementia.

Serotonin [5-hydroxytryptamine (5-HT)]-absorbing neurons use serotonin reuptake transporter (SERT) to uptake 5-HT from extracellular space but do not synthesize it. While 5-HT-absorbing neurons have been identified in diverse organisms from Caenorhabditis elegans to humans, their function has not been elucidated. Here, we show that SERT in 5-HT-absorbing neurons controls behavioral response to food deprivation in C. elegans. The AIM and RIH interneurons uptake 5-HT released from chemosensory neurons and secretory neurons. Genetic analyses suggest that 5-HT secreted by both synaptic vesicles and dense core vesicles diffuse readily to the extrasynaptic space adjacent to the AIM and RIH neurons. Loss of mod-5/SERT function blocks the 5-HT absorption. mod-5/SERT mutants have been shown to exhibit exaggerated locomotor response to food deprivation. We found that transgenic expression of MOD-5/SERT in the 5-HT-absorbing neurons fully corrected the exaggerated behavior. Experiments of cell-specific inhibition of synaptic transmission suggest that the synaptic release of 5-HT from the 5-HT-absorbing neurons is not required for this behavioral modulation. Our data point to the role of 5-HT-absorbing neurons as temporal-spatial regulators of extrasynaptic 5-HT. Regulation of extrasynaptic 5-HT levels by 5-HT-absorbing neurons may represent a fundamental mechanism of 5-HT homeostasis, integrating the activity of 5-HT-producing neurons with distant targets in the neural circuits, and could be relevant to some actions of selective serotonin reuptake inhibitors in humans.

Cerebral serotonin metabolism has an important but controversial role in obesity. However, it is not given enough attention in morbidly obese young adults. We used single photon emission computed tomography (SPECT) with [I-123]-labeled 2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine (ADAM) to investigate changes in serotonintransporter (SERT) availability in 10 morbidly obese young adults without an eating disorder (M/F = 5/5, body mass index (BMI): 40.3 ± 4.1 kg/m2, percentage of body fat (BF%): 46.0 ± 3.9%) and 10 age- and sex-matched non-obese controls (BMI: 20.3 ± 1.2 kg/m2, BF%: 20.6 ± 8.9%). All participants underwent SPECT at 10 min and 6 h after an injection of 200 MBq of [I-123]-ADAM. The SERT binding site (midbrain) was drawn with cerebellum normalization. The BF% and fat distribution were measured using dual-energy X-ray absorptiometry. The midbrain/cerebellum SERT binding ratios (2.49 ± 0.46 vs. 2.47 ± 0.47; p = 0.912) at 6 h were not significantly different between groups, nor was the distribution of the summed images at 10 min (1.36 ± 0.14 vs. 1.35 ± 0.11; p = 0.853). There were no significant correlations between midbrain/cerebellum SERT binding ratio and age, BMI, BF%, or fat distribution. No significant difference in SERT availability in the midbrain between morbidly obese and non-obese young adults without an eating disorder indicates an unmet need for investigating the role of cerebral serotonin in obesity. PMID:28182708

The local injurious effects of traffic appear mostly in densely populated areas, where the demand for transport is high. The local environmental effects of transportation can be reduced by measures of urban planning, traffic planning, vehicle technology and economical restrictions. Land use planning, concentration of urban structure and promoting distance working are examples of expedients of urban planning. The methods of urban planning usually affect very slowly on transport structure, but they also have a significant and continuous influence on travel demand. The methods of traffic planning generally tend to increase the fluency of traffic flow or reduce private car traffic with diverse restrictions by supporting environmentally more favourable vehicles or modes of travel. The improvements in vehicle technology can be significant in the short run. By economical regulations it is possible to guide the demand for traffic to a desirable direction. The local injurious effects of traffic vary by the size of urban areas. Local conditions, such as urban structure, population density, structure of employment, and composition of transport structure, influence on travel pattern and modal split. In Tampere University of Technology several measures to reduce environmental effects and energy consumption of transportation has been evaluated. This article presents three types of categories. As technological measures the introduction of electric vehicles and the alternative bus fuels have been studied. In addition, the effects of introducing midibuses, the car pool system and the increasing of vehicle occupancy have been evaluated as measures, which generally increase transportation system efficiency. (author)

The human serotonintransporter (hSERT) regulates the spatial and temporal actions of serotonin (5-HT) neurotransmission by removing 5-HT from the synapse. Previous studies have identified residues in the third transmembrane helix (TMH) that may be important for substrate translocation or antagonist recognition. We identified hSERT residues in TMH III that are divergent from Drosophila SERT and used species-scanning mutagenesis to generate reciprocal mutants. Transport inhibition assays suggest that the potency of substituted amphetamines was decreased for the hSERT mutants A169D, I172M, and S174M. In addition, there was a loss of potency for several antidepressants and 3-phenyltropane analogs for the I172M mutant. These results suggest that residues in TMH III may contribute to antagonist recognition. We carried out comparative molecular field analyses using selectivity fields to directly visualize the mutation-induced effects of antagonist potency for antidepressants, 3-phenyltropane analogs, and amphetamines. The hSERT I172M selectivity field analysis for the 3-phenyltropane analogs revealed that electrostatic interactions resulted in decreased potency. The amphetamine and antidepressant selectivity field analyses reveal the observed decreases in potencies for the hSERT I172M mutant are due to a change in tertiary structure of the hSERT protein and are not due to disruption of a direct binding site. Finally, the hSERT mutant A169D displayed altered kinetics for sodium binding, indicating that this residue may lie near the putative sodium binding site. A SERT homology model developed from the Aquifex aeolicus leucine transporter structure provides a structural context for further interpreting the results of the TMH III mutations.

This study was conducted to determine the effects of Phellinus linteus (PL) on serotonin synthesis in the brain and on the expression of monocarboxylate transporters (MCTs) in muscles during exhaustive exercise in rats. In this study, 60 male Sprague-Dawley rats were divided into the following 6 groups: control; exercise; exercise and 50 mg/kg of PL treatment; exercise and 100 of mg/kg PL treatment; exercise and 200 mg/kg of PL treatment; and exercise and 100 mg/kg of caffeine treatment. Treatment with 200 mg/kg of PL led to a significant increase in the time to exhaustion in response to running on a treadmill and a significant decrease in 5-hydroxytryptamine synthesis and tryptophan hydroxylase expression in the dorsal raphe of rats. MCT1 and MCT4 expression of the gastrocnemius muscles was also increased in response to treatment with 200 mg/kg of PL. The results of the present study demonstrated that the administration of PL increased endurance exercise performance through inhibition of serotonin production in the brain and increased the expression of MCT1 and MCT4 in muscles. These results suggest that PL exerts an ergogenic effect.

Serotonin (5-HT) function is altered in several psychiatric disorders, including cocaine dependence (CD), and its role in impulsive-aggressive behaviors has been widely studied. However, the relationship between psychopathological and behavioral dimensions and mechanisms of 5-HT alterations remains unclear. We investigated the relationship of a polymorphism in the 5' promoter region of the serotonintransporter gene (5-HTTLPR) with prolactin (PRL) response to meta-chlorophenylpiperazine (m-CPP) in a sample of 68 African-American individuals, 35 CD subjects and 33 controls. We also examined whether measures of impulsivity, hostility and sensation seeking influenced the relationship between the 5-HTTLPR polymorphism and PRL response to m-CPP in this sample. Individuals with the SS genotype showed significantly heightened PRL response to the challenge compared with the LL and LS genotypes. No influence of gender or substance abuse condition was observed. Hostility was associated with blunted PRL response in the total sample. Cocaine abuse was the most significant moderator of DeltaPRL (peak PRL-baseline PRL), and the interaction of genetic, behavioral and psychopathological measures helped predict most of the observed DeltaPRL (62.5%). Although these results need replication, variation in the 5-HTTLPR gene appears to influence measures of 5-HT function and interact with disease state and personality dimensions to account for 5-HT disturbances in African-American populations.

The serotonintransporter (5-HTT) regulates serotonergic neurotransmission via clearance of extracellular serotonin. Abnormalities in 5-HTT expression or function are found in mood and anxiety disorders, and the 5-HTT is a major target for antidepressants and anxiolytics. The 5-HTT is further implicated in the pathophysiology of these disorders by evidence that genetic variation in the promoter region of the HTT (SLC6A4) is associated with individual differences in anxiety and neural responses to fear. To further evaluate the role of the 5-HTT in anxiety, we employed a mouse model in which the 5-HTT gene (htt) was constitutively inactivated. 5-HTT -/- mice were characterized for anxiety-related behaviors using a battery of tests (elevated plus maze, lightdark exploration test, emergence test, and open field test). Male and female 5-HTT -/- mice showed robust phenotypic abnormalities as compared to +/+ littermates, suggestive of increased anxiety-like behavior and inhibited exploratory locomotion. The selective 5-HT(1A) receptor antagonist, WAY 100635 (0.05-0.3 mg/kg), produced a significant anxiolytic-like effect in the elevated plus maze in 5-HTT -/- mice, but not +/+ controls. The present findings demonstrate abnormal behavioral phenotypes in 5-HTT null mutant mice in tests for anxiety-like and exploratory behavior, and suggest a role for the 5-HT(1A) receptor in mediating these abnormalities. 5-HTT null mutant mice provide a model to investigate the role of the 5-HTT in mood and anxiety disorders.

Full Text Available Abstract Background There is evidence from animal studies that serotonin (5-HT can influence the antinociceptive effects of opioids at the spinal cord level. Therefore, there could be an influence of genetic polymorphisms in the serotonin system on individual variability in response to opioid treatment of pain. The serotonintransporter (5-HTT is a key regulator of serotonin metabolism and availability and its gene harbors several known polymorphisms that are known to affect 5-HTT expression (e.g. 5-HTTLPR, rs25531. The aim of this study was to investigate if the triallelic 5-HTTLPR influences pain sensitivity or the analgesic effect of opioids in humans. 43 healthy volunteers (12 men, 31 women, mean age 26 years underwent heat pain stimulations before and after intravenous injection of Remifentanil; a rapid and potent opioid drug acting on μ-type receptors. Subjects rated their perceived pain on a visual analogue scale (VAS. All participants were genotyped for the 5-HTTLPR and the rs25531 polymorphism. We recruited by advertising, with no history of drug abuse, chronic pain or psychiatric disorders. Results At baseline, there was no difference in pain ratings for the different triallelic 5-HTTLPR genotype groups. However, the opiod drug had a differential analgesic effect depending on the triallelic 5-HTTLPR genotype. Remifentanil had a significantly better analgesic effect in individuals with a genotype coding for low 5-HTT expression (SA/SA and SA/LG as compared to those with high expression(LA/LA, p Conclusion This is the first report showing an influence of the triallelic 5-HTTLPR on pain sensitivity or the analgesic effect of opioids in humans. Previously the 5-HTTLPR s-allele has been associated with higher risk of developing chronic pain conditions but in this study we show that the genotype coding for low 5-HTT expression is associated with a better analgesic effect of an opioid. The s-allele has been associated with downregulation of

Manipulating tree belowground carbon (C) transport enables investigation of the ecological and physiological roles of tree roots and their associated mycorrhizal fungi, as well as a range of other soil organisms and processes. Girdling remains the most reliable method for manipulating this flux and it has been used in numerous studies. However, girdling is destructive and irreversible. Belowground C transport is mediated by phloem tissue, pressurized through the high osmotic potential resulting from its high content of soluble sugars. We speculated that phloem transport may be reversibly blocked through the application of an external pressure on tree stems. Thus, we here introduce a technique based on compression of the phloem, which interrupts belowground flow of assimilates, but allows trees to recover when the external pressure is removed. Metal clamps were wrapped around the stems and tightened to achieve a pressure theoretically sufficient to collapse the phloem tissue, thereby aiming to block transport. The compression's performance was tested in two field experiments: a (13)C canopy labelling study conducted on small Scots pine (Pinus sylvestris L.) trees [2-3 m tall, 3-7 cm diameter at breast height (DBH)] and a larger study involving mature pines (∼15 m tall, 15-25 cm DBH) where stem respiration, phloem and root carbohydrate contents, and soil CO2 efflux were measured. The compression's effectiveness was demonstrated by the successful blockage of (13)C transport. Stem compression doubled stem respiration above treatment, reduced soil CO2 efflux by 34% and reduced phloem sucrose content by 50% compared with control trees. Stem respiration and soil CO2 efflux returned to normal within 3 weeks after pressure release, and (13)C labelling revealed recovery of phloem function the following year. Thus, we show that belowground phloem C transport can be reduced by compression, and we also demonstrate that trees recover after treatment, resuming C

The serotonintransporter (SERT) is the primary target for antidepressant drugs. The existence of a high affinity primary orthosteric binding site (S1) and a low affinity secondary site (S2) has been described, and their relation to antidepressant pharmacology has been debated. Herein, structural...

analysis revealed a positive correlation between pain tolerance and SERT binding in the hypothalamus (r = 0.53; p = 0.02) although this was not seen in the parametric analysis. These data extend our earlier observation that cortical 5-HT receptors co-determine responses to tonic but not to phasic pain......There is a large body of evidence that the serotonergic system plays an important role in the transmission and regulation of pain. Here we used positron emission tomography (PET) with the serotonintransporter (SERT) tracer [11C]DASB to study the relationship between SERT binding in the brain...... and responses to noxious heat stimulation in a group of 21 young healthy volunteers. Responses to noxious heat stimuli were assessed in a separate psychophysical experiment and included measurements of pain threshold, pain tolerance, and responses to phasic noxious heat stimuli and to a long lasting (7-minute...

Alzheimer's disease (AD) has been treated with acetylcholinesterase (AChE) inhibitors such as donepezil. However, the clinical usefulness of AChE inhibitors is limited mainly due to their adverse peripheral effects. Depression seen in AD patients has been treated with serotonintransporter (SERT) inhibitors. We considered that combining SERT and AChE inhibition could improve the clinical usefulness of AChE inhibitors. In a previous paper, we found a potential dual inhibitor, 1, of AChE (IC50=101 nM) and SERT (IC50=42 nM), but its AChE inhibition activity was less than donepezil (IC50=10 nM). Here, we report the conformationally restricted (R)-18a considerably enhanced inhibitory activity against AChE (IC50=14 nM) and SERT (IC50=6 nM).

We have designed and synthesized a dual inhibitor of acetylcholinesterase (AChE) and serotonintransporter (SERT) as a novel class of treatment drugs for Alzheimer's disease on the basis of a hypothetical model of the AChE active site. Dual inhibitions of AChE and SERT would bring about greater therapeutic effects than AChE inhibition alone and avoid adverse peripheral effects caused by excessive AChE inhibition. Compound (S)-6j exhibited potent inhibitory activities against AChE (IC(50)=101 nM) and SERT (IC(50)=42 nM). Furthermore, (S)-6j showed inhibitory activities of both AChE and SERT in mice brain following oral administration.

Full Text Available Depression is a major health problem for which most patients are not effectively treated. This problem is further compounded in children and adolescents where only two antidepressants [both selective serotonin reuptake inhibitors (SSRIs] are currently approved for clinical use. Mouse models provide tools to identify mechanisms that might account for poor treatment response to antidepressants. However, there are few studies in adolescent mice and none in juvenile mice. The tail suspension test (TST is commonly used to assay for antidepressant-like effects of drugs in adult mice. Here we show that the TST can also be used to assay antidepressant-like effects of drugs in C57Bl/6 mice aged 21 (juvenile and 28 (adolescent days post-partum (P. We found that the magnitude of antidepressant-like response to the SSRI escitalopram was less in P21 mice than in P28 or adult mice. The smaller antidepressant response of juveniles was not related to either maximal binding (Bmax or affinity (Kd for [3H]citalopram binding to the serotonintransporter (SERT in hippocampus, which did not vary significantly among ages. Magnitude of antidepressant-like response to the tricyclic desipramine was similar among ages, as were Bmax and Kd values for [3H]nisoxetine binding to the norepinephrine transporter (NET in hippocampus. Together, these findings suggest that juvenile mice are less responsive to the antidepressant-like effects of escitalopram than adults, but that this effect is not due to delayed maturation of SERT in hippocampus. Showing that the TST is a relevant behavioral assay of antidepressant-like activity in juvenile and adolescent mice sets the stage for future studies of the mechanisms underlying the antidepressant response in these young populations.

Full Text Available Children born very preterm are exposed to repeated neonatal procedures that induce pain and stress during hospitalization in the neonatal intensive care unit (NICU. The COMT Val158Met genotype is involved with pain sensitivity, and early life stress is implicated in altered expression of methylation of the serotonintransporter. We examined: (1 whether methylation of the serotonintransporter gene (SLC6A4 promoter differs between very preterm children and full-term controls at school age, (2 relationships with child behavior problems, and (3 whether the extent of neonatal pain exposure interacts with the COMT Val158Met genotype to predict SLC6A4 methylation at 7 years in the very preterm children. We examined the associations between the COMT genotypes, neonatal pain exposure (adjusted for neonatal clinical confounders, SLC6A4 methylation and behavior problems. Very preterm children had significantly higher methylation at 7/10 CpG sites in the SLC6A4 promoter compared to full-term controls at 7 years. Neonatal pain (adjusted for clinical confounders was significantly associated with total child behaviour problems on the Child Behavior Checklist (CBCL questionnaire (adjusted for concurrent stressors and 5HTTLPR genotype (p = 0.035. CBCL total problems was significantly associated with greater SLC6A4 methylation in very preterm children (p = 0.01. Neonatal pain (adjusted for clinical confounders and COMT Met/Met genotype were associated with SLC6A4 promoter methylation in very preterm children at 7 years (p = 0.001. These findings provide evidence that both genetic predisposition and early environment need to be considered in understanding susceptibility for developing behavioral problems in this vulnerable population.

Evidence of marked variability in response among people exposed to the same environmental risk implies that individual differences in genetic susceptibility might be at work. The study of such Gene-by-Environment (G×E) interactions has gained momentum. In this article, the authors review research about one of the most extensive areas of inquiry: variation in the promoter region of the serotonintransporter gene (SLC6A4; also known as 5-HTT) and its contribution to stress sensitivity. Research in this area has both advanced basic science and generated broader lessons for studying complex diseases and traits. The authors evaluate four lines of evidence about the 5-HTT stress-sensitivity hypothesis: 1) observational studies about the serotonintransporter linked polymorphic region (5-HTTLPR), stress sensitivity, and depression in humans; 2) experimental neuroscience studies about the 5-HTTLPR and biological phenotypes relevant to the human stress response; 3) studies of 5-HTT variation and stress sensitivity in nonhuman primates; and 4) studies of stress sensitivity and genetically engineered 5-HTT mutations in rodents. The authors then dispel some misconceptions and offer recommendations for G×E research. The authors discuss how G×E interaction hypotheses can be tested with large and small samples, how G×E research can be carried out before as well as after replicated gene discovery, the uses of G×E research as a tool for gene discovery, the importance of construct validation in evaluating G×E research, and the contribution of G×E research to the public understanding of genetic science. PMID:20231323

Serotonintransporter (SERT) is a critical determinant of synaptic serotonin (5-hydroxytryptamine, 5-HT) inactivation which plays a critical role in the pathology of depression and other mood disorders. Lipopolysaccharide (LPS), a potent activator of the inflammatory system, has been reported to cause depression symptoms by the modulation of SERT in vivo and in vitro. This study is aimed to investigate the underlying mechanism of LPS-induced SERT modulation. The 4-(4-(dimethylamino) styryl)-N-methylpyridinium iodide (ASP) assay was used to detect dynamic 5-HT uptake as read out of SERT activities in RBL-2H3 cells, and cytosol Ca(2+) concentrations ([Ca(2+)]i) and nitric oxide (NO) were examined. Using specific cyclic GMP-dependent protein kinase type I (PKG-I), p38 mitogen-activated protein kinases (p38MAPK) and A3 adenosine receptor (A3AR) inhibitors, SERT expression was evaluated by western blot and immunofluorescence analysis. Results showed that 24 h treatment with LPS stimulated 5-HT transport and up-regulate plasma membrane distribution of SERT in RBL-2H3 cells. LPS treatment increased NO and [Ca(2+)]i, and led to significant increases in levels of phosphorylated calcium/calmodulin-dependent protein kinase type II (CaMK-II), inducible NOS (iNOS) and PKG-I as well as active p38 MAPK. Moreover, PKG-I inhibitor KT5823 or p38MAPK inhibitor SB203580 respectively impaired SERT activation and transposition to plasma membrane by LPS. Notably, A3 adenosine receptor inhibitor MRS1191 also hindered SERT stimulation by LPS. In conclusion, LPS-induced 5-HT uptake and transposition to plasma membrane of SERT in RBL-2H3 cells involves CaMK-II/iNOS/PKG-I and p38 MAPK activation, which may be partially mediated by A3 adenosine receptor activation. This finding provides a novel insight into the interrelationship between LPS and depression.

Full Text Available In the United States, two thirds of the carbon monoxide and about one third of carbon dioxide emissions come from the transportation sector. Ways to reduce these emissions in the future include replacing gasoline and diesel by biofuels, or by blend of biofuels with conventional gasoline and diesel, or by compressed natural gas (CNG, or by replacing internal combustion engines by electric motors powered by hydrogen fuel cells or battery-powered electric vehicles recharged from the electric grid. This presentation will review these technologies the fuel production pathways, when they are likely to be available, and by what fraction transportation sector green house gas emissions could be reduced by each. A well-to-wheels (WTW analysis is performed on each vehicle/ fuel technology using the GREET model and the total energy use, the CO 2 emissions, NO x emissions, SO x emissions for the life cycle of the vehicle technologies are calculated. Prospects for reducing foreign oil dependence as well as mitigating green house gases emission from the transportation sector will be considered in the analysis.

Full Text Available BACKGROUND: Shift-working nurses are exposed to a stressful work environment, which puts them at an increased risk for burnout and depression. We explored the effect of environmental stress on serotonintransporter gene (SLC6A4 promoter methylation among nurses from high and low work stress environments. METHODOLOGY: Using bisulfite sequencing, we investigated the methylation status of five CpG residues of a CpG-rich region in the promoter of SLC6A4 by comparing female shift working nurses from a high work stress environment (n = 24 to low work stress environment (n = 25. We also analyzed the association of 5-HTTLPR polymorphism at 5' end of SLC6A4. Work stress was assessed by the Karasek's Model and possible signs of burnout or depression were measured by the Maslach Burnout Index General Survey and Beck Depression Index. Methylation levels were assessed by bisulfite sequencing of DNA extracted from peripheral blood leucocytes. Restriction enzyme treatment followed by standard PCR was used to identify 5-HTTLPR genotypes. PRINCIPAL FINDINGS: We found that nurses in the high stress environment had significantly lower promoter methylation levels at all five CpG residues compared to nurses in the low stress environment (p<0.01. There was no significant interaction of 5-HTTLPR genotype and work stress with methylation (p = 0.58. In unadjusted (bivariate analysis, burnout was not significantly associated to methylation levels. However, when mutually adjusted for both, burnout and work stress were significant contributors (p = 0.038 and p<0.0001 respectively to methylation levels. CONCLUSIONS: Our findings show that environmental stress is concurrent with decreased methylation of the SLC6A4 promoter. This may lead to increased transcriptional activity of the gene, increased reuptake of serotonin from synaptic clefts, and termination of the activity of serotonin. This could present a possible coping mechanism for environmental stress in humans that

In this study, we examined the relative efficacies of alpha-tocopherol, N-acetyl-serotonin, and melatonin in reducing ascorbate-Fe(2+) lipid peroxidation (LPO) of rat testicular microsomes and mitochondria. Special attention was paid to the changes produced on the highly polyunsaturated fatty acids (PUFAs) C20:4 n6 and C22:5 n6. The LPO of testicular microsomes or mitochondria produced a significant decrease of C20:4 n6 and C22:5 n6. Both long-chain PUFAs were protected when the antioxidants were incorporated either in microsomes or mitochondria. By comparison of the IC50 values obtained between alpha-tocopherol and both indolamines, it was observed that alpha-tocopherol was the most efficient antioxidant against the LPO induced by ascorbate-Fe(2+) under experimental conditions in vitro, IC50 values from the inhibition of alpha-tocopherol on the chemiluminescence were higher in microsomes (0.14 mM) than in mitochondria (0.08 mM). The protective effect observed by alpha-tocopherol in rat testis mitochondria was higher compared with microsomes, associated with the higher amount of [C20:4 n6] + [C22:5 n6] in microsomes than that in mitochondria. Melatonin and N-acetyl-serotonin were more effective in inhibiting the LPO in mitochondria than that in microsomes. Thus, a concentration of 1 mM of both indolamines was sufficient to inhibit in approximately 70% of the light emission in mitochondria, whereas a greater dosage of 10 times (10 mM) was necessary to produce the same effect in microsomes. It is proposed that the vulnerability to LPO of rat testicular microsomes and mitochondria in the presence of both indolamines is different because of the different proportion of PUFAs in these organelles.

The tracer {sup 123}I-2-([2-({l_brace}dimethylamino{r_brace}methyl)phenyl]thio)-5-iodophenylamine ([{sup 123}I]ADAM) has been developed to image serotonintransporters (SERTs) with SPECT. Preclinical studies have shown that [{sup 123}I]ADAM binds selectively to SERTs. Moreover, initial human studies have shown that [{sup 123}I]ADAM binding could be blocked by selective serotonin reuptake inhibitors (SSRIs). However, in humans it has not been proven that [{sup 123}I]ADAM binds selectively to SERTs. We examined the in vivo availability of SERTs in 12 healthy young volunteers 5 h after bolus injection of [{sup 123}I]ADAM. To evaluate the selectivity of binding, four participants were pretreated (double-blinded design) with placebo, four with paroxetine (20 mg) and four with the dopamine/norepinephrine blocker methylphenidate (20 mg). SPECT studies were performed on a brain-dedicated system (Neurofocus), and the SPECT images were coregistered with individual MR scans of the brain. ADAM binding in SERT-rich brain areas and cerebellar cortex (representing non-specific binding) was assessed by drawing regions of interest (ROIs) on the individual MR images. Specific to non-specific ratios were used as the outcome measure. We found that specific to non-specific ratios were statistically significantly lower in paroxetine-pretreated participants than in placebo- or methylphenidate-pretreated participants. No such difference was found between groups pretreated with placebo or methylphenidate. Our preliminary findings suggest that [{sup 123}I]ADAM binds selectively to SERTs in human brain. (orig.)

The serotonin system is undoubtedly involved in the pathogenesis of major depressive disorder (MDD). More specifically the serotonintransporter (SERT) serves as a major target for antidepressant drugs. There are conflicting results about SERT availability in depressed patients versus healthy controls. We aimed to measure SERT availability and study the effects of age, gender and season of scanning in MDD patients in comparison to healthy controls. We included 49 depressed outpatients (mean{+-}SD 42.3 {+-} 8.3 years) with a Hamilton depression rating scale score above 18, who were drug-naive or drug-free for {>=}4 weeks, and 49 healthy controls matched for age ({+-}2 years) and sex. Subjects were scanned with single photon emission computed tomography (SPECT) using [{sup 123}I]{beta}-CIT. SERT availability was expressed as specific to nonspecific binding ratios (BP{sub ND}) in the midbrain and diencephalon with cerebellar binding as a reference. In crude comparisons between patients and controls, we found no significant differences in midbrain or diencephalon SERT availability. In subgroup analyses, depressed males had numerically lower midbrain SERT availability than controls, whereas among women SERT availability was not different (significant diagnosis x gender interaction; p = 0.048). In the diencephalon we found a comparable diagnosis x gender interaction (p = 0.002) and an additional smoking x gender (p = 0.036) interaction. In the midbrain the season of scanning showed a significant main effect (p = 0.018) with higher SERT availability in winter. Differences in SERT availability in the midbrain and diencephalon in MDD patients compared with healthy subjects are affected by gender. The season of scanning is a covariate in the midbrain. The diagnosis x gender and gender x smoking interactions in SERT availability should be considered in future studies of the pathogenesis of MDD. (orig.)

Full Text Available The serotonintransporter gene (5-HTTLPR influences emotional reactivity and attentional bias towards or away from emotional stimuli and has been implicated in psychopathological states, such as depression and anxiety disorder. The short allele is associated with increased reactivity and attention towards negatively-valenced emotional information, whereas the long allele is associated with that towards positively-valenced emotional information. The neural basis for individual differences in the ability to exert cognitive control over these bottom-up biases in emotional reactivity and attention is unknown, an issue investigated in the present study. Two groups, homozygous 5-HTTLPR long allele carriers or homozygous short allele carriers, underwent functional magnetic resonance imaging (fMRI while completing an Emotional Stroop-like task that varied with regards to the congruency of task-relevant and task-irrelevant information and the emotional valence of the task-irrelevant information. Behaviorally, participants demonstrated the classic Stroop effect (slower responses for incongruent than congruent trials, which did not differ by 5-HTTLPR genotype. However, fMRI results revealed that genotype influenced the degree to which neural systems were engaged depending on the valence of the conflicting task-irrelevant information. While the Long group recruited prefrontal control regions and superior temporal sulcus during conflict when task-irrelevant information was positively-valenced, the "Short" group recruited these regions when task-irrelevant information was negatively-valenced. Thus, participants successfully engaged cognitive control to overcome conflict in an emotional context using similar neural circuitry, but the engagement of this circuitry depended on emotional valence and 5-HTTLPR status. These results suggest that the interplay between emotion and cognition is modulated, in part, by a genetic polymorphism that influences serotonin

There is evidence that temperamental factors are associated with obesity; however, the biological mechanism of such association remains elusive. We aimed to investigate a possible association between serotonin transmission and regulative temperament in obese and non-obese individuals by using positron emission tomography (PET) imaging of serotonintransporters (SERT) and the Adult Temperament Questionnaire. Twenty-nine obese individuals with body mass index (BMI) ≥ 35 kg/m(2) and 13 non-obese controls (BMI

A functional polymorphism in the promoter region of the 5-hidroxytryptamine transporter gene (5-HTTLPR), alters its transcription. Short allele (SS) variation decreases the transcriptional efficacy of serotonin, causing psychiatric disorders, major depressive disorder (MDD) and major depression in response to stressful life events. The aim of this study was to determine the current understanding of the role of 5-HTTLPR polymorphism in the development of depressive episodes and its response to treatment. Twenty-five articles were identified from PubMed, utilizing the following keyword, 5-HTT transporter gene, polymorphism, depression, stressful condition, psychiatric disorder. All articles were read and notes were made regarding study participant, measures, data analysis and results, and were used to write this review. The distribution of the SS allele in patients is associated with an increased risk of MDD following exposure to stressful events of life. Additionally, this genetic variant is closely associated with several psychiatric conditions such as suicidal behaviour, psychoses, personality disorders, and aggressive-impulsive traits.

Background Elevated cholesterol and triglycerides in blood lead to atherosclerosis and fatty liver, contributing to rising cardiovascular and hepatobiliary morbidity and mortality worldwide. Methods and Results A cell‐penetrating nuclear transport modifier (NTM) reduced hyperlipidemia, atherosclerosis, and fatty liver in low‐density lipoprotein receptor‐deficient mice fed a Western diet. NTM treatment led to lower cholesterol and triglyceride levels in blood compared with control animals (36% and 53%, respectively; Ptriglyceride, and fatty acid synthesis. NTM‐modulated translocation of SREBPs to the nucleus was associated with attenuated transactivation of their cognate genes that contribute to hyperlipidemia. Conclusions Two‐pronged control of inflammation and dyslipidemia by modulating nuclear transport of their critical regulators offers a new approach to comprehensive amelioration of hyperlipidemia, atherosclerosis, fatty liver, and their potential complications. PMID:23563994

Hypofunction of the serotonergic system is often associated with major depression and obsessive compulsive disorder (OCD). Selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed to treat these disorders, and require 3-6 weeks of chronic treatment before improvements in the symptoms are observed. SSRIs inhibit serotonin's transporter, and in doing so, increase extracellular serotonin concentrations. Thus, efficacy of SSRIs likely depends upon the brain's adaptive response to sustained increases in serotonin levels. Individual responsiveness to SSRI treatment may depend on a variety of factors that influence these changes, including ongoing stress. Social isolation is a passive, naturalistic form of chronic mild stress that can model depression in rodents. In this study, we examined how 20-day treatment with the SSRI citalopram (CIT) alters marble-burying (MB), open field behavior, and serotonin signaling in single- vs pair-housed animals. We used in vivo voltammetry to measure electrically evoked serotonin, comparing release rate, net overflow, and clearance. Pair-housed mice were significantly more responsive to CIT treatment, exhibiting reduced MB and facilitation of serotonin release that positively correlated with the frequency of electrical stimulation. These effects of CIT treatment were attenuated in single-housed mice. Notably, although CIT treatment enhanced serotonin release in pair-housed mice, it did not significantly alter uptake rate. In summary, we report that chronic SSRI treatment facilitates serotonin release in a frequency-dependent manner, and this effect is blocked by social isolation. These findings suggest that the efficacy of SSRIs in treating depression and OCD may depend on ongoing stressors during treatment.

Evidence suggests that increases in synaptic serotonin (5-HT) can reduce the stimulant properties of amphetamine-type drugs. Here we tested the hypothesis that administration of the 5-HT precursor 5-hydroxy-l-tryptophan (5-HTP), along with the peripheral decarboxylase inhibitor benserazide, would decrease locomotor effects of (+)-amphetamine. Drug treatments were administered to conscious male rats undergoing in vivo microdialysis in nucleus accumbens. During dialysis sampling, rats were housed in chambers equipped with photobeams to detect forward locomotion (i.e., ambulation) and repetitive movements (i.e., stereotypy). Extracellular concentrations of dopamine (DA) and 5-HT were measured by high-pressure liquid chromatography with electrochemical detection. 5-HTP (10 & 30 mg/kg, i.p.) plus benserazide (30 mg/kg, i.p.) caused dose-related increases in 5-HT but failed to alter other parameters. (+)-Amphetamine (0.3 & 1.0 mg/kg, i.p.) produced dose-related increases in DA, ambulation and stereotypy. Combined administration of 5-HTP and (+)-amphetamine evoked large elevations in extracellular DA and 5-HT, but caused significantly less ambulation than (+)-amphetamine alone (~50% reduction). Our results confirm that 5-HTP can decrease hyperactivity produced by (+)-amphetamine, even in the presence of elevations in dialysate DA. The data suggest that 5-HTP and (+)-amphetamine may be useful to broadly enhance monoamine function in the clinical setting, while reducing undesirable effects of (+)-amphetamine. Published by Elsevier Ireland Ltd.

Spinal cord transection leads to elimination of brain stem-derived monoamine fibers that normally synthesize most of the monoamines in the spinal cord, including serotonin (5-hydroxytryptamine, 5-HT) synthesized from tryptophan by enzymes tryptophan hydroxylase (TPH, synthesizing 5-hydroxytryptophan, 5-HTP) and aromatic l-amino acid decarboxylase (AADC, synthesizing 5-HT from 5-HTP). Here we examine whether spinal cord caudal to transection remains able to manufacture and metabolize 5-HT. Immunolabeling for AADC reveals that, while most AADC is confined to brain stem-derived monoamine fibers in spinal cords from normal rats, caudal to transection AADC is primarily found in blood vessel endothelial cells and pericytes as well as a novel group of neurons (NeuN positive and GFAP negative), all of which strongly upregulate AADC with injury. However, immunolabeling for 5-HT reveals that there is no detectable endogenous 5-HT synthesis in any structure in the spinal cord caudal to a chronic transection, including in AADC-containing vessels and neurons, consistent with a lack of TPH. In contrast, when we applied exogenous 5-HTP (in vitro or in vivo), AADC-containing vessels and neurons synthesized 5-HT, which contributed to increased motoneuron activity and muscle spasms (long-lasting reflexes, LLRs), by acting on 5-HT2 receptors (SB206553 sensitive) located on motoneurons (TTX resistant). Blocking monoamine oxidase (MAO) markedly increased the sensitivity of the motoneurons (LLR) to 5-HTP, more than it increased the sensitivity of motoneurons to 5-HT, suggesting that 5-HT synthesized from AADC is largely metabolized in AADC-containing neurons and vessels. In summary, after spinal cord injury AADC is upregulated in vessels, pericytes, and neurons but does not endogenously produce 5-HT, whereas when exogenous 5-HTP is provided AADC does produce functional amounts of 5-HT, some of which is able to escape metabolism by MAO, diffuse out of these AADC-containing cells, and

The paper deals with the actual problem of increasing the safety of operation of belt conveyors in mines. Was developed the control algorithm that meets the technical requirements of the mine belt conveyors, reduces the risk of fires of conveyors belt, and enables energy and resource savings taking into account random sort of traffic. The most effective method of decision such tasks is the construction of control systems with the use of variable speed drives for asynchronous motors. Was designed the mathematical model of the system "variable speed multiengine drive - conveyor - control system of conveyors", that takes into account the dynamic processes occurring in the elements of the transport system, provides an assessment of the energy efficiency of application the developed algorithms, which allows to reduce the dynamic overload in the belt to (15-20)%.

Mutations in the C terminus of the serotonintransporter (SERT) disrupt folding and export from the endoplasmic reticulum. Here we examined the hypothesis that a cytosolic heat shock protein relay was recruited to the C terminus to assist folding of SERT. This conjecture was verified by the following observations. (i) The proximal portion of the SERT C terminus conforms to a canonical binding site for DnaK/heat shock protein of 70 kDa (HSP70). A peptide covering this segment stimulated ATPase activity of purified HSP70-1A. (ii) A GST fusion protein comprising the C terminus of SERT pulled down HSP70-1A. The interaction between HSP70-1A and SERT was visualized in live cells by Förster resonance energy transfer: it was restricted to endoplasmic reticulum-resident transporters and enhanced by an inhibitor that traps HSP70-1A in its closed state. (iv) Co-immunoprecipitation confirmed complex formation of SERT with HSP70-1A and HSP90β. Consistent with an HSP relay, co-chaperones (e.g. HSC70-HSP90-organizing protein) were co-immunoprecipitated with the stalled mutants SERT-R607A/I608A and SERT-P601A/G602A. (v) Depletion of HSP90β by siRNA or its inhibition increased the cell surface expression of wild type SERT and SERT-F604Q. In contrast, SERT-R607A/I608A and SERT-P601A/G602A were only rendered susceptible to inhibition of HSP70 and HSP90 by concomitant pharmacochaperoning with noribogaine. (vi) In JAR cells, inhibition of HSP90 also increased the levels of SERT, indicating that endogenously expressed transporter was also susceptible to control by HSP90β. These findings support the concept that the folding trajectory of SERT is sampled by a cytoplasmic chaperone relay.

Full Text Available Polymorphisms that alter serotonintransporter SERT expression and functionality increase the risks for autism and psychiatric traits. Here, we investigate how SERT controls serotonin signaling in developing CNS in mice. SERT is transiently expressed in specific sets of glutamatergic neurons and uptakes extrasynaptic serotonin during perinatal CNS development. We show that SERT expression in glutamatergic thalamocortical axons (TCAs dictates sensory map architecture. Knockout of SERT in TCAs causes lasting alterations in TCA patterning, spatial organizations of cortical neurons, and dendritic arborization in sensory cortex. Pharmacological reduction of serotonin synthesis during the first postnatal week rescues sensory maps in SERTGluΔ mice. Furthermore, knockdown of SERT expression in serotonin-producing neurons does not impair barrel maps. We propose that spatiotemporal SERT expression in non-serotonin-producing neurons represents a determinant in early life genetic programming of cortical circuits. Perturbing this SERT function could be involved in the origin of sensory and cognitive deficits associated with neurodevelopmental disorders.

Affinities of arylpiperazinylalkyl derivatives of imidazo[2,1-f]purine-2,4-dione and imidazolidine-2,4-dione for serotonintransporter and their acid-base properties were evaluated. The dissociation constant (pK(a)) of compounds 1-22 were determinated by potentiometric titration and calculated using pKalc 3.1 module of the Pallas system. The data from experimental methods and computational calculations were compared and suitable conclusions were reached.

The incidence of aggressive behavior in patients with schizophrenia is higher than in the general population. Among particular gene polymorphisms posited to be involved in psychiatric disorders, the catecholamine-O-methyltransferase (COMT) and serotonintransporter (5-HTTPR) genes have been the focus of recent research on aggression. In this study, we hypothesized that both the COMT and the 5-HTTPR genotypes may be dependent on and related to aggression in Korean patients with schizophrenia. The subjects were 168 unrelated male schizophrenic patients diagnosed according to DSM-IV. Among two psychiatric hospital staff and medical university students, 158 unrelated male subjects with no lifetime history of psychiatric disorders were recruited to establish the COMT and 5-HTTPR genotype distribution in the general population. All episodes of aggression from the last discharge to readmission were rated. The Total Overt Aggression Scale (OAS) score (sum of the scores of all episodes of aggression), highest OAS score (highest individual episode score, 0-16), OAS category, and OAS category score (mean score within each category) were recorded. There were statistically significant effects of COMT genotype on the mean OAS 4 (physical aggression against other people) score and the highest OAS score. The most predictive was the OAS 4 score. There was a statistically significant effect of 5-HTTPR genotype on mean total score. Thus, the COMT gene is associated with the severity of aggression and with physical aggression against other people, whereas the 5-HTTPR gene is associated with the summary score of all episodes of aggression.

Full Text Available Several studies have been conducted to analyze the role of short polymorphism of serotonintransporter (5-HTTLPR in response to psy-chosocial stress mediated by cortisol, having found inconsistent results. In order to synthesize and analyze available information about the role of short polymorphisms of 5-HTTLPR gen in the stress response, this meta-analysis has been carried out. A meta-analysis of studies published until November 2011 without language restrictions, which analyzed the effect of the short polymorphisms of 5-HTTLPR in the cortisol response during a stress-inducing protocol was conducted. Published F or p genotype values were collected as estimators of the difference between groups as well as the sign of this difference for analysis. The global meta-analysis showed no significant association between the presence of the short allele and a different response to psychosocial stress. After comparing the subgroups of studies where participants underwent an emotionally neutral intervention versus an emotionally negative intervention, significant differences were found. The subgroup of studies where patients underwent an emotionally negative intervention showed a significantly greater cortisol release by those individuals carrying the short allele. This association was not seen in the neutral subgroup.

Full Text Available Abstract Background The aim of this study is to assess the association between the SerotoninTransporter Promoter Polymorphism (5-HTTLPR and Panic Disorder (PD. Methods This is a systematic review and meta-analysis of case-control studies with unrelated individuals of any ethnic origin examining the role of the 5-HTTLPR in PD according to standard diagnostic criteria (DSM or ICD. Articles published in any language between January 1996 and April 2007 were eligible. The electronic databases searched included PubMed, PsychInfo, Lilacs and ISI. Two separate analyses were performed: an analysis by alleles and a stratified analysis separating studies by the quality of control groups. Asymptotic DerSimonian and Laird's Q test were used to assess heterogeneity. Results of individual studies were combined using the fixed effect model with respective 95% confidence intervals. Results Nineteen potential articles were identified, and 10 studies were included in this meta-analysis. No statistically significant association between 5-HTTLPR and PD was found, OR = 0.91 (CI95% 0.80 to 1.03, p = 0.14. Three sub-analyses divided by ethnicity, control group quality and Agoraphobia comorbidity also failed to find any significant association. No evidence of heterogeneity was found between studies in the analyses. Conclusion Results from this systematic review do not provide evidence to support an association between 5-HTTLPR and PD. However, more studies are needed in different ethnic populations in order to evaluate a possible minor effect.

The role of the serotonintransporter gene-linked polymorphic region (5-HTTLPR) in anxiety disorder and anxiety-related traits is controversial. Besides this study, few studies have evaluated the triallelic genotype in adolescents. The aim of this study was to investigate whether anxiety disorders and anxiety-related traits are associated with 5-HTTLPR (biallelic and triallelic) in adolescents, integrating both case-control-based and family-based designs in a community sample. This is a cross-sectional community study of 504 individuals and their families: 225 adolescents (129 adolescents with anxiety disorder and 96 controls) and their biological families. We assessed psychiatric diagnosis using the Kiddie Schedule for Affective Disorders and Schizophrenia. The Temperament and Character Inventory and the Resnick Behavioral Inhibition Scale were used to evaluate harm avoidance and behavioral inhibition. DNA was extracted from saliva and genotyped, including biallelic and triallelic 5-HTTLPR classification, by PCR-RFLP followed by agarose gel electrophoresis. We were not able to find any associations between 5-HTTLPR and anxiety-related phenotypes in both case-control and trio analyses. Further investigation and meta-analytic studies are needed to better clarify the inconsistent results with regard to the association between 5-HTTLPR and anxiety-related phenotypes in adolescents.

Studies support a link between adolescent romantic involvement and depression. Adolescent romantic relationships may increase depression risk by introducing chronic stress, and genetic vulnerability to stress reactivity/emotion dysregulation may moderate these associations. We tested genetic moderation of longitudinal associations between adolescent romantic involvement and later depressive symptoms by a polymorphism in the serotonintransporter linked polymorphic region gene (5-HTTLPR) and examined contributory roles of chronic stress and family discord. Three hundred eighty-one youth participated at ages 15 and 20. The results indicated that 5-HTTLPR moderated the association between age 15 romantic involvement and age 20 depressive symptoms, with strongest effects for short homozygotes. Conditional process analysis revealed that chronic stress functioned as a moderated mediator of this association, fully accounting for the romantic involvement-depression link among short/short genotypes. Also, romantic involvement predicted later depressive symptoms most strongly among short-allele carriers with high family discord. The results have important implications for understanding the romantic involvement-depression link and the behavioral and emotional correlates of the 5-HTTLPR genotype.

This study was designed to assess whether functional magnetic resonance imaging (fMRI) following antidepressant administration (pharmaco-fMRI) is sufficiently sensitive to detect differences in patterns of activation between enantiomers of the same compound. Healthy adult males (n=11) participated in a randomized, double-blind, cross-over trial with three medication periods during which they received citalopram (racemic mixture), escitalopram (S-citalopram alone), or placebo for 2 weeks. All participants had high expression serotonintransporter genotypes. An fMRI scan that included passive viewing of overt and covert affective faces and affective words was performed after each medication period. Activation in response to overt faces was greater following escitalopram than following citalopram in the right insula, thalamus, and putamen when the faces were compared with a fixation stimulus. For the rapid covert presentation, a greater response was observed in the left middle temporal gyrus in the happy versus fearful contrast following escitalopram than following citalopram. Thus, the combination of genomics and fMRI was successful in discriminating between two very similar drugs. However, the pattern of activation observed suggests that further studies are indicated to understand how to optimally combine the two techniques.

Whereas molecular imaging studies in the aging human brain have predominantly demonstrated reductions in serotonintransporter (5-HTT) availability, the majority of the rodent studies, using autoradiographic methods, report increases in neural 5-HTT levels with age. To our knowledge, however, no previous rodent studies have assessed this topic in vivo, and therefore it remains unclear whether this discrepancy arises from methodological or inter-species differences. We performed an [(11)C]-DASB microPET study to evaluate the effects of aging on 5-HTT availability in the rat brain. To generate binding potential estimates, quantitative tracer kinetic modeling was applied using the simplified reference tissue model. A global increase in whole-brain [(11)C]-DASB binding potential was observed in the aged rats in comparison to the control group. More specifically, regional analyses revealed a highly significant increase in 5-HTT binding in the medial frontal cortex, and more modest increments in the midbrain/thalamus. Our results suggest that the frontal cortex represents a site of robust age-related alterations in the rat serotonergic system, and stress the need for further research assessing this topic in the human frontal cortex. Moreover, these findings suggest that the reported discrepancies between rodent and human data may reflect a divergence in the aging processes affecting human and rat serotonergic terminals.

N,N-Dimethyl-2-(2-amino-4-methylthiophenylthio)benzylamine (S Me-Adam, 1) is a highly potent and selective inhibitor of the serotonintransporter (SPERT). This compound was labeled with carbon-11 by methylation of the S-desmethyl precursor 10 with [{sup 11}C]methyl iodide to obtain the potential positron emission tomography (PET) radioligand [{sup 11}C]S Me-Adam. The radiochemical yield was 27{+-}5%, and the specific radioactivity was 26-40 GBq/{mu}mol at the end of synthesis. Ex vivo and in vivo biodistribution experiments in rats demonstrated a rapid accumulation of the radiotracer in brain regions known to be rich in SPERT, such as the thalamus/hypothalamus region (3.59{+-}0.41%ID/g at 5 min after injection). The specific uptake reached a thalamus to cerebellum ratio of 6.74{+-}0.95 at 60 min postinjection. The [{sup 11}C]SMe-ADAM uptake in the thalamus was significantly decreased by pretreatment with fluoxetine to 38{+-}11% of the control value. Furthermore, no metabolites of [{sup 11}C]SMe-ADAM could be detected in the SERT-rich regions of the rat brain. It is concluded that [{sup 11}C]SMe-ADAM may be a suitable PET ligand for SERT imaging in the living brain.

Full Text Available Abstract Background Over the past decade pediatric bipolar disorder has gained recognition as a potentially more severe and heritable form of the disorder. In this report we test for association with genes coding brain-derived neurotrophic factor (BDNF, the serotonintransporter (SLC6A4, and catechol-O-methyltransferase (COMT. Methods Bipolar-I affected offspring triads (N = 173 were drawn from 522 individuals with 2 parents in 332 nuclear families recruited for genetic studies of pediatric psychopathology at the Clinical and Research Program in Pediatric Psychopharmacology and Adult ADHD at Massachusetts General Hospital. Results We failed to identify an association with the val66 allele in BDNF (OR = 1.23, p = 0.36, the COMT-l allele (OR = 1.27, p = 0.1, or the HTTLPR short allele (OR = 0.87, p = 0.38. Conclusion Our study suggests that the markers examined thus far in COMT and SLC6A4 are not associated with pediatric bipolar disorder and that if the val66met marker in BDNF is associated with pediatric bipolar disorder the magnitude of the association is much smaller than first reported.

We examined 89 normal volunteers using Cloninger's Temperament and Character Inventory (TCI). Genotyping the 102T/C polymorphism of the serotonin 5HT2A receptor gene and the ser9gly polymorphism in exon 1 of the dopamine D3 receptor (DRD3) gene was performed using PCR-RFLP, whereas the dopamine transporter (DAT1) gene variable number of tandem repeats (VNTR) polymorphism was investigated using PCR amplification followed by electrophoresis in an 8% acrylamide gel with a set of size markers. We found a nominally significant association between gender and harm avoidance (P=0.017; women showing higher scores). There was no association of either DAT1, DRD3 or 5HT2A alleles or genotypes with any dimension of the TCI applying Kruskal-Wallis rank-sum tests. Comparing homozygote and heterozygote DAT1 genotypes, we found higher novelty seeking scores in homozygotes (P=0.054). We further found a nominally significant interaction between DAT1 and 5HT2A homo-/heterozygous gene variants (P=0.0071; DAT1 and 5HT2A genotypes P value of 0.05), performing multivariate analysis of variance (MANOVA). Examining the temperamental TCI subscales, this interaction was associated with persistence (genotypes: P=0.004; homo-/heterozygous gene variants: P=0.0004). We conclude that an interaction between DAT1 and 5HT2A genes might influence the temperamental personality trait persistence.

We addressed the question whether 5-HTTLPR, a variable number of tandem repeats located in the 5' end of the serotonintransporter gene, is associated with smoking or alcohol consumption. Samples of DNA from 1,365 elderly women with a mean age of 69.2 years were genotyped for this polymorphism using a procedure, which allowed the simultaneous determination of variation in the number of repeat units and single nucleotide changes, including the A > G variation at rs25531 for discrimination between the L(A) and L(G) alleles. Qualitative and quantitative information on the women's current and previous consumption of cigarettes and alcohol were obtained using a questionnaire. Genotypes were classified according to allele size, that is, S and L with 14 and 16 repeat units, respectively, and on a functional basis by amalgamation of the L(G) and S alleles. Data were subjected to regression analyses. These analyses revealed P values for associations between 5-HTTLPR genotype and alcohol and cigarette consumption in the range from 0.15 to 0.92. On adjustment for age and educational level, significance for the associations of 5-HTTLPR with the smoking and alcohol consumption measures was not reached. We conclude that 5-HTTLPR is not an important determinant of smoking behavior and alcohol consumption in elderly women.

Neuroticism has been linked to a functional polymorphism in the serotonintransporter gene (5-HTTLPR), with short-allele carriers being overrepresented among high-scorers on neuroticism. Studies evaluating neuroticism-related personality traits in relation to the 5-HTTLPR polymorphism among patients with premenstrual dysphoric disorder (PMDD) and are lacking. The primary aim of this study was to evaluate the relationship between PMDD and neuroticism-related personality traits, and secondly, to relate the personality trait scores of PMDD patients to experienced symptom severity and to the 5-HTTLPR short allele. Thirty PMDD patients and 55 asymptomatic healthy controls were included in the study. The Swedish Universities Scale of Personality was used to evaluate personality traits. Genotype analyses were available in 27 PMDD patients and 18 healthy controls. Women with PMDD displayed higher levels of neuroticism-related personality traits (psychic trait anxiety, somatic trait anxiety, embitterment, stress susceptibility and mistrust) than healthy controls, and these effects were most prominent in women with more severe luteal phase symptoms. Furthermore, PMDD patients with at least one copy of the short allele of the 5-HTTLPR polymorphism scored higher on psychic trait anxiety and lack of assertiveness than PMDD patients who were homozygous for the long allele. PMDD patients who suffer from more severe luteal phase symptoms also display increased scores of neuroticism-related personality traits in comparison with healthy controls. Within the group of PMDD patients, differences in certain personality trait scores are associated with the short allele of the 5-HTTLPR polymorphism.

A functional polymorphism (5-HTTLPR) within the serotonintransporter gene (SERT) has been associated with personality dimensions such as neuroticism, with emotional reactivity to negative events, and with an increased risk of affective disorders. More specifically, the short (S) allele of 5-HTTLPR has been linked to increased amygdala activity and has been identified as a risk allele for depressive disorders. Recently, Homberg and Lesch (2011) urged for a conceptual change in the current deficit-oriented connotation of the 5-HTTLPR S-allele and argued that the S-allele could be considered adaptive in certain contexts. They postulated that S-allele carriers show hypervigilant behavior in social situations and should thus show increased social conformity. Therefore, we tested whether 5-HTTLPR modulates the neural correlates of real-life social joint action through functional near-infrared spectroscopy (fNIRS). Thirty participants, homozygote for 5-HTTLPR, were measured and analyzed while they were involved in a previously published joint-action paradigm, which reliably leads to an activation of the left parietal cortex. We found that homozygote S-allele carriers showed increased inferior parietal lobe activation, compared to the LL-allele carriers for the contrast "joint action greater solo action". Therefore, our results provide evidence for beneficial effects of the S-allele on the neural correlates of social interactions.

Imaging of serotonintransporter (SERT) by positron emission tomography (PET) or single-photon emission-computed tomography (SPECT) in humans would provide useful information in diagnosis and therapy of several neurodegenerative and neuropsychiatric disorders. 6-Nitroquipazine is a highly potent and selective inhibitor of the SERT. For the development of new {sup 99m}Tc-labeled 6-nitroquipazine derivatives as SERT imaging agents, novel [N-[2-((3-(4-(6-nitroquinolin-2-yl)piperazin-1-yl)propyl)(2-mercaptoethyl) amino]-acetyl-2-aminoethanethiolato] [{sup 99m}Tc]technetium (V) oxide ({sup 99m}Tc-MAMA-3-PQ) and its rhenium analog were synthesized and characterized. {sup 99m}Tc-MAMA-3-PQ displayed high initial brain uptake (0.52% ID/organ at 2 min post-injection (pi)) and relatively fast washout in mice (0.09% ID/organ at 60 min pi). The regional brain distribution studies in rats showed high-specific binding ratios at 60 min pi. Maximum regional contrast ratio observed for thalamus/cerebellum was 2.94, followed by 2.62 for hypothalamus/cerebellum. These encouraging results lead us to further explore its derivatives as new imaging agents for the SERT in the brain.

N,N-Dimethyl-2-(2-amino-4-methylthiophenylthio)benzylamine (SMe-ADAM, 1) is a highly potent and selective inhibitor of the serotonintransporter (SERT). This compound was labeled with carbon-11 by methylation of the S-desmethyl precursor 10 with [(11)C]methyl iodide to obtain the potential positron emission tomography (PET) radioligand [(11)C]SMe-ADAM. The radiochemical yield was 27 +/- 5%, and the specific radioactivity was 26-40 GBq/micromol at the end of synthesis. Ex vivo and in vivo biodistribution experiments in rats demonstrated a rapid accumulation of the radiotracer in brain regions known to be rich in SERT, such as the thalamus/hypothalamus region (3.59 +/- 0.41%ID/g at 5 min after injection). The specific uptake reached a thalamus to cerebellum ratio of 6.74 +/- 0.95 at 60 min postinjection. The [(11)C]SMe-ADAM uptake in the thalamus was significantly decreased by pretreatment with fluoxetine to 38 +/- 11% of the control value. Furthermore, no metabolites of [(11)C]SMe-ADAM could be detected in the SERT-rich regions of the rat brain. It is concluded that [(11)C]SMe-ADAM may be a suitable PET ligand for SERT imaging in the living brain.

Evidence of semi-starvation is commonly found in patients with eating disorders. This study was conducted to examine the adverse effects of chronic caloric restriction in young rats, since there have been increasing incidence of eating disorders especially among young populations. Food restriction group was supplied daily with 50% of chow consumed by its ad libitum fed control group from postnatal day 28. After 5 weeks of food restriction, brain contents of serotonin (5-hydroxy-tryptamine; 5-HT) and its metabolite 5-hydroxyindol acetic acid were analyzed by high-performance liquid chromatography and mRNA expression of 5-HT reuptake transporter (5-HTT) by in situ hybridization. Plasma corticosterone levels were determined by radioimmunoassay. Behavioral assessments were performed with Porsolt swim test for depressive behavior and with elevated plus maze test for anxiety. Five weeks of food restriction markedly increased plasma level of corticosterone, and significantly decreased 5-HT turnover rates in the hippocampus and the hypothalamus. 5-HTT mRNA expression decreased in the raphe nucleus of food restricted rats compared with free fed controls. Immobility time during the swim test increased in the food restricted group, compared to the control group. Food restricted rats spent more time in the closed arms, less time in the open arms, of elevated plus maze compared with control rats. These results suggest that chronic caloric restriction in young rats may lead to the development of depressive and/or anxiety disorders, likely, in relation with dysfunction of brain 5-HT system.

Background The aim of this study is to assess the association between the SerotoninTransporter Promoter Polymorphism (5-HTTLPR) and Panic Disorder (PD). Methods This is a systematic review and meta-analysis of case-control studies with unrelated individuals of any ethnic origin examining the role of the 5-HTTLPR in PD according to standard diagnostic criteria (DSM or ICD). Articles published in any language between January 1996 and April 2007 were eligible. The electronic databases searched included PubMed, PsychInfo, Lilacs and ISI. Two separate analyses were performed: an analysis by alleles and a stratified analysis separating studies by the quality of control groups. Asymptotic DerSimonian and Laird's Q test were used to assess heterogeneity. Results of individual studies were combined using the fixed effect model with respective 95% confidence intervals. Results Nineteen potential articles were identified, and 10 studies were included in this meta-analysis. No statistically significant association between 5-HTTLPR and PD was found, OR = 0.91 (CI95% 0.80 to 1.03, p = 0.14). Three sub-analyses divided by ethnicity, control group quality and Agoraphobia comorbidity also failed to find any significant association. No evidence of heterogeneity was found between studies in the analyses. Conclusion Results from this systematic review do not provide evidence to support an association between 5-HTTLPR and PD. However, more studies are needed in different ethnic populations in order to evaluate a possible minor effect. PMID:17705872

To develop a potential SPECT probe to evaluate the integrity of the serotoninergic system (5-HTT) whose dysfunction is linked to several disease conditions such as Parkinson’s, Alzheimer’s diseases and depression, we report the synthesis, radiolabeling and in vivo baboon imaging of 2β-carbomethoxy-3β-(3′-[123I]iodophenyl) tropane (YP256, 6). The radiolabeling was performed by iododestannylation using sodium [123I]iodide and peracetic acid. Although the ligand displayed high selectivity for 5-HTT over dopamine transporter (DAT) in vitro, SPECT imaging in baboons did not reveal selective 5-HTT accumulation in brain in vivo. PMID:18158943

Full Text Available Background & Aims:Malfunctions of enteric neurons are believed to play an important role in the pathophysiology of irritable bowel syndrome (IBS. Our aim was to investigate whether neuronal activity in biopsies from IBS patients is altered in comparison to healthy controls (HC.Methods:Activity of human submucous neurons in response to electrical nerve stimulation and local application of nicotine or a mixture of histamine, serotonin, tryptase and TNF-α (IBS-cocktail was recorded in biopsies from 17 HC and 35 IBS patients with the calcium-sensitive-dye Fluo-4 AM. The concentrations of the mediators resembeled those found in biopsy supernatants or blood. Neuronal activity in guinea-pig submucous neurons was studied with the voltage-sensitive-dye di-8-ANEPPS. Results:Activity in submucous ganglia in response to nicotine or electrical nerve stimulation was not different between HC and IBS patients (P=0.097 or P=0.448. However, the neuronal response after application of the IBS-cocktail was significantly decreased (P=0.039 independent of whether diarrhea (n=12, constipation (n=5 or bloating (n=5 was the predominant symptom. In agreement with this we found that responses of submucous ganglia conditioned by overnight incubation with IBS mucosal biopsy supernatant to spritz application of this supernatant was significantly reduced (P=0.019 when compared to incubation with HC supernatant.Conclusion:We demonstrated for the first time reduced neuronal responses in mucosal IBS biopsies to an IBS mediator cocktail. While excitability to classical stimuli of enteric neurons was comparable to HC, the activation by the IBS-cocktail was decreased. This was very likely due to desensitization to mediators constantly released by mucosal and immune cells in the gut wall of IBS patients.

Full Text Available We investigated the effects of bilateral injections of the GABA receptor agonists muscimol (GABA A and baclofen (GABA B into the nucleus tractus solitarius (NTS on the bradycardia and hypotension induced by iv serotonin injections (5-HT, 2 µg/rat in awake male Holtzman rats. 5-HT was injected in rats with stainless steel cannulas implanted bilaterally in the NTS, before and 5, 15, and 60 min after bilateral injections of muscimol or baclofen into the NTS. The responses to 5-HT were tested before and after the injection of atropine methyl bromide. Muscimol (50 pmol/50 nl, N = 8 into the NTS increased basal mean arterial pressure (MAP from 115 ± 4 to 144 ± 6 mmHg, did not change basal heart rate (HR and reduced the bradycardia (-40 ± 14 and -73 ± 26 bpm at 5 and 15 min, respectively, vs -180 ± 20 bpm for the control and hypotension (-11 ± 4 and -14 ± 4 mmHg, vs -40 ± 9 mmHg for the control elicited by 5-HT. Baclofen (12.5 pmol/50 nl, N = 7 into the NTS also increased basal MAP, but did not change basal HR, bradycardia or hypotension in response to 5-HT injections. Atropine methyl bromide (1 mg/kg body weight injected iv reduced the bradycardic and hypotensive responses to 5-HT injections. The stimulation of GABA A receptors in the NTS of awake rats elicits a significant increase in basal MAP and decreases the cardiac Bezold-Jarisch reflex responses to iv 5-HT injections.

Full Text Available According to the Ministry of Transport inland water transport is one of the five modes of transport in our country play a very important role. Inland waterway transport not only plays a major role in transporting large volumes of goods and passengers but also creates millions of jobs contributing to ensuring social security and national defense and security. However there are still many inadequacies in waterway transportation such as unequal waterway traffic The phenomenon of exploitation of river resources as planned or Process technology is not as planned exploitation of sand gravel etc. are common in most rivers and canals in the country. The signaling system is not synchronized between the signal of the inland waterway management unit and the signal of the owner The handling of domestic goods transportation and inland port management is inadequate The force of the means of development is fast uneven but concentrated in some urban areas and industrial parks. Therefore the Ministry of Transport has proposed a scheme to facilitate the development of a synchronized inland waterway infrastructure linking with other modes of transport To improve the capacity of the crew and the inland waterway transport crews. To create favorable conditions for inland waterway transportation business with reasonable transportation costs Improve the quality of water transport services Ensure safety and environmental friendliness Make a distinct advantage over other modes of transport. Specifically will develop promulgate mechanisms The policy is to facilitate the development of inland waterway infrastructure Build and promulgate mechanism The policy of supporting the development of the fleet has a reasonable structure with a fleet of about 30 self-propelled ships accounting for about 70 of the total number of inland waterway vessels To prioritize the development of the container fleet Inland waterway transportation and training retraining of human resources for

Mutations in the C terminus of the serotonintransporter (SERT) disrupt folding and export from the endoplasmic reticulum. Here we examined the hypothesis that a cytosolic heat shock protein relay was recruited to the C terminus to assist folding of SERT. This conjecture was verified by the following observations. (i) The proximal portion of the SERT C terminus conforms to a canonical binding site for DnaK/heat shock protein of 70 kDa (HSP70). A peptide covering this segment stimulated ATPase activity of purified HSP70-1A. (ii) A GST fusion protein comprising the C terminus of SERT pulled down HSP70-1A. The interaction between HSP70-1A and SERT was visualized in live cells by Förster resonance energy transfer: it was restricted to endoplasmic reticulum-resident transporters and enhanced by an inhibitor that traps HSP70-1A in its closed state. (iv) Co-immunoprecipitation confirmed complex formation of SERT with HSP70-1A and HSP90β. Consistent with an HSP relay, co-chaperones (e.g. HSC70-HSP90-organizing protein) were co-immunoprecipitated with the stalled mutants SERT-R607A/I608A and SERT-P601A/G602A. (v) Depletion of HSP90β by siRNA or its inhibition increased the cell surface expression of wild type SERT and SERT-F604Q. In contrast, SERT-R607A/I608A and SERT-P601A/G602A were only rendered susceptible to inhibition of HSP70 and HSP90 by concomitant pharmacochaperoning with noribogaine. (vi) In JAR cells, inhibition of HSP90 also increased the levels of SERT, indicating that endogenously expressed transporter was also susceptible to control by HSP90β. These findings support the concept that the folding trajectory of SERT is sampled by a cytoplasmic chaperone relay. PMID:25202009

Mucosal inflammation in conditions ranging from infective acute enteritis or colitis to inflammatory bowel disease is accompanied by alteration in serotonin (5-hydroxytryptamine [5-HT]) content in the gut. Recently, we have identified an important role of 5-HT in the pathogenesis of experimental colitis. 5-HT type 7 (5-HT7) receptor is one of the most recently identified members of the 5-HT receptor family, and dendritic cells express this receptor. In this study, we investigated the effect of blocking 5-HT7 receptor signaling in experimental colitis with a view to develop an improved therapeutic strategy in intestinal inflammatory disorders. Colitis was induced with dextran sulfate sodium (DSS) or dinitrobenzene sulfonic acid (DNBS) in mice treated with selective 5-HT7 receptor antagonist SB-269970, as well as in mice lacking 5-HT7 receptor (5-HT7(-/-)) and irradiated wild-type mice reconstituted with bone marrow cells harvested from 5-HT7(-/-) mice. Inhibition of 5-HT7 receptor signaling with SB-269970 ameliorated both acute and chronic colitis induced by DSS. Treatment with SB-269970 resulted in lower clinical disease, histological damage, and proinflammatory cytokine levels compared with vehicle-treated mice post-DSS. Colitis severity was significantly lower in 5-HT7(-/-) mice and in mice reconstituted with bone marrow cells from 5-HT7(-/-) mice compared with control mice after DSS colitis. 5-HT7(-/-) mice also had significantly reduced DNBS-induced colitis. These observations provide us with novel information on the critical role of the 5-HT7 receptor in immune response and inflammation in the gut, and highlight the potential benefit of targeting this receptor to alleviate the severity of intestinal inflammatory disorders such as inflammatory bowel disease.

Prolonged stress perturbs physiological balance of a subject and thus can lead to depression. Nevertheless, some individuals are more resilient to stress than the others. Defining molecular factors underlying resilience to stress may contribute to the development of a new antidepressant strategy based on the restoration of resilient phenotype in depressed subjects. We used chronic mild stress (CMS) paradigm-well-characterized animal model of depression which caused in rats behavioral deficits (anhedonia) manifested by decreased consumption of sucrose solution. CMS also generated a proportion of resilient rats which did not alter sucrose consumption despite being stressed. Recently, regulation of a gene expression associated with microRNA (miRNA) is considered as an important factor modulating biochemical response to stress. Based on our previous work and literature survey, we investigated changes in the expression level of seven miRNAs (i.e., miR-18a-5p, miR-34a-5p, miR-135a-5p, miR-195-5p, miR-320-3p, miR-674-3p, miR-872-5p) in mesocortical circuit-crucially involved in stress response in order to find differences between susceptible and resilient phenotype. Bioinformatic analysis showed that all miRNAs of interest potentially target serotonintransporter (SERT). Chronic stress caused global increase in the expression of the abovementioned miRNAs in ventral tegmental area (VTA) of stressed rats followed by parallel decrease in miRNA expression in prefrontal cortex (PCx). This effect was more profound in resilient than anhedonic animals. Moreover, we observed decreased level of SERT in VTA of resilient rats. Our findings show that mesocortical circuit is involved in the response to stress and this phenomenon is more efficient in resilient animals.

Full Text Available The low transcriptionally efficient short-allele of the 5HTTLPR serotonintransporter polymorphism has been implicated to moderate the relationship between the experience of stressful life events (SLEs and depression. Despite numerous attempts at replicating this observation, results remain inconclusive.We examined this relationship in young-adult Non-Hispanic white males and females between the ages of 22 and 26 (n = 4724 participating in the National Longitudinal Study of Adolescent to Adult Health (Add Health with follow-up information every six years since 1995.Linear and logistic regression models, corrected for multiple testing, indicated that carriers of one or more of the S-alleles were more sensitive to stress than those with two L-alleles and at a higher risk for depression. This relationship behaved in a dose-response manner such that the risk for depression was greatest among those who reported experiencing higher numbers of SLEs. In post-hoc analyses we were not able to replicate an interaction effect for suicide ideation but did find suggestive evidence that the effects of SLEs and 5HTTLPR on suicide ideation differed for males and females. There were no effects of childhood maltreatment.Our results provide partial support for the original hypothesis that 5-HTTLPR genotype interacts with the experience of stressful life events in the etiology of depression during young adulthood. However, even with this large sample, and a carefully constructed a priori analysis plan, the results were still not definitive. For the purposes of replication, characterizing the 5HTTLPR in other large data sets with extensive environmental and depression measures is needed.

Background Genetic and environmental factors shape life-long vulnerability to depression, but most gene–environment interaction (G×E) research has focused on cross-sectional assessments rather than life-course phenotypes. This study tests the hypothesis that the G×E involving the length polymorphism in the serotonin-transporter-gene-linked-promoter-region (5-HTTLPR) and childhood maltreatment is specific to depression that runs a persistent course in adulthood. Methods The hypothesis is tested in two cohorts. Men and women in the Dunedin Study (N=847), New Zealand, followed to age 32 years with 96% retention and women in the E-Risk Study (N=930), England, followed to age 40 years with 96% retention. Diagnoses of past-year major depressive episode were established at four separate assessments. Depression diagnosed on two or more occasions was considered persistent. Results In both cohorts, statistical tests of gene–environment interactions showed positive results for persistent depression but not single-episode depression. Individuals with two short 5-HTTLPR alleles and childhood maltreatment had elevated risk of persistent but not single-episode depression. Limitations Some cases of recurrent depression may have been misclassified as single-episode due to non-contiguous assessment windows, but this would have a conservative effect on the findings. Chronic and recurrent depression could not be reliably distinguished due to non-contiguous periods of assessment. Therefore, the term persistent depression is used to describe either chronic or recurrent course. Conclusions The specific effect on persistent depression increases the significance of this G×E for public health. Research that does not distinguish persistent course may underestimate G×E effects and account for some replication failures in G×E research. PMID:21439648

BACKGROUND The STin2 VNTR polymorphism has a variable number of tandem repeats in intron 2 of the serotonintransporter gene. We aimed to explore the relationship between STin2 VNTR polymorphism and lifelong premature ejaculation (LPE). MATERIAL AND METHODS We recruited a total of 115 outpatients who complained of ejaculating prematurely and who were diagnosed as LPE, and 101 controls without PE complaint. Allelic variations of STin2 VNTR were genotyped using PCR-based technology. We evaluated the associations between STin2 VNTR allelic and genotypic frequencies and LPE, as well as the intravaginal ejaculation latency time (IELT) of different STin2 VNTR genotypes among LPE patients. RESULTS The patients and controls did not differ significantly in terms of any characteristic except age. A significantly higher frequency of STin2.12/12 genotype was found among LPE patients versus controls (P=0.026). Frequency of patients carrying at least 1 copy of the 10-repeat allele was significantly lower compared to the control group (28.3% vs. 41.8%, OR=0.55; 95%CI=0.31-0.97, P=0.040). In the LPE group, the mean IELT showed significant difference in STin2.12/12 genotype when compared to those with STin2.12/10 and STin2.10/10 genotypes. The mean IELT in10-repeat allele carriers was 50% longer compared to homozygous carriers of the STin2.12 allele. CONCLUSIONS Our results indicate the presence of STin2.10 allele is a protective factor for LPE. Men carrying the higher expression genotype STin2. 12/12 have shorter IELT than 10-repeat allele carriers.

Background The STin2 VNTR polymorphism has a variable number of tandem repeats in intron 2 of the serotonintransporter gene. We aimed to explore the relationship between STin2 VNTR polymorphism and lifelong premature ejaculation (LPE). Material/Methods We recruited a total of 115 outpatients who complained of ejaculating prematurely and who were diagnosed as LPE, and 101 controls without PE complaint. Allelic variations of STin2 VNTR were genotyped using PCR-based technology. We evaluated the associations between STin2 VNTR allelic and genotypic frequencies and LPE, as well as the intravaginal ejaculation latency time (IELT) of different STin2 VNTR genotypes among LPE patients. Results The patients and controls did not differ significantly in terms of any characteristic except age. A significantly higher frequency of STin2.12/12 genotype was found among LPE patients versus controls (P=0.026). Frequency of patients carrying at least 1 copy of the 10-repeat allele was significantly lower compared to the control group (28.3% vs. 41.8%, OR=0.55; 95%CI=0.31–0.97, P=0.040). In the LPE group, the mean IELT showed significant difference in STin2.12/12 genotype when compared to those with STin2.12/10 and STin2.10/10 genotypes. The mean IELT in10-repeat allele carriers was 50% longer compared to homozygous carriers of the STin2.12 allele. Conclusions Our results indicate the presence of STin2.10 allele is a protective factor for LPE. Men carrying the higher expression genotype STin2. 12/12 have shorter IELT than 10-repeat allele carriers. PMID:27713390

The role of the central serotonin (5-hydroxytryptamine, 5-HT) system in feeding has been extensively studied in animals with the 5-HT family of transporters (5-HTT) being identified as key molecules in the regulation of satiety and body weight. Aberrant 5-HT transmission has been implicated in the pathogenesis of human obesity by in vivo positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging techniques. However, results obtained thus far from studies of central 5-HTT availability have been inconsistent, which is thought to be brought about mainly by the low number of individuals with a high body mass index (BMI) previously used. The aim of this study was therefore to assess 5-HTT availability in the brains of highly obese otherwise healthy individuals compared with non-obese healthy controls. We performed PET using the 5-HTT selective radiotracer [{sup 11}C] DASB on 30 highly obese (BMI range between 35 and 55 kg/m{sup 2}) and 15 age- and sex-matched non-obese volunteers (BMI range between 19 and 27 kg/m{sup 2}) in a cross-sectional study design. The 5-HTT binding potential (BP{sub ND}) was used as the outcome parameter. On a group level, there was no significant difference in 5-HTT BP{sub ND} in various cortical and subcortical regions in individuals with the highest BMI compared with non-obese controls, while statistical models showed minor effects of age, sex, and the degree of depression on 5-HTT BP{sub ND}. The overall finding of a lack of significantly altered 5-HTT availability together with its high variance in obese individuals justifies the investigation of individual behavioral responses to external and internal cues which may further define distinct phenotypes and subgroups in human obesity. (orig.)

Individuals with anorexia nervosa (AN) and bulimia nervosa (BN) have alterations of measures of serotonin (5-HT) and dopamine (DA) function, which persist after long-term recovery and are associated with elevated harm avoidance (HA), a measure of anxiety and behavioral inhibition. Based on theories that 5-HT is an aversive motivational system that may oppose a DA-related appetitive system, we explored interactions of positron emission tomography (PET) radioligand measures that reflect portions of these systems. Twenty-seven individuals recovered (REC) from eating disorders (EDs) (7 AN-BN, 11 AN, 9 BN) and nine control women (CW) were analyzed for correlations between [(11)C]McN5652 and [(11)C]raclopride binding. There was a significant positive correlation between [(11)C]McN5652 binding potential (BP(non displaceable(ND))) and [(11)C]Raclopride BP(ND) for the dorsal caudate, antero-ventral striatum (AVS), middle caudate, and ventral and dorsal putamen. No significant correlations were found in CW. [(11)C]Raclopride BP(ND), but not [(11)C]McN5652 BP(ND), was significantly related to HA in REC EDs. A linear regression analysis showed that the interaction between [(11)C]McN5652 BP(ND) and [(11)C]raclopride BP(ND) in the dorsal putamen significantly predicted HA. This is the first study using PET and the radioligands [(11)C]McN5652 and [(11)C]raclopride to show a direct relationship between 5-HT transporter and striatal DA D2/D3 receptor binding in humans, supporting the possibility that 5-HT and DA interactions contribute to HA behaviors in EDs.

Gene-environment interaction effects in predicting antisocial behavior in late childhood were investigated among maltreated and nonmaltreated low-income children (N = 627, M age = 11.27). Variants in three genes were examined: tryptophan hydroxylase 1 (TPH1), serotonintransporter linked polymorphic region (5-HTTLPR), and monoamine oxidase A (MAOA) upstream variable number tandem repeat. In addition to child maltreatment status, we considered the impact of maltreatment subtypes, developmental timing of maltreatment, and chronicity. Indicators of antisocial behavior were obtained from self-, peer, and adult counselor reports. In a series of analyses of covariance, child maltreatment and its parameters demonstrated strong main effects on early antisocial behavior as assessed by all report forms. Genetic effects operated primarily in the context of gene-environment interactions, moderating the impact of child maltreatment on outcomes. Across the three genes, among nonmaltreated children no differences in antisocial behavior were found based on genetic variation. In contrast, among maltreated children specific polymorphisms of TPH1, 5-HTTLPR, and MAOA were each related to heightened self-report of antisocial behavior; the interaction of 5-HTTLPR and developmental timing of maltreatment also indicated more severe antisocial outcomes for children with early onset and recurrent maltreatment based on genotype. TPH1 and 5-HTTLPR interacted with maltreatment subtype to predict peer reports of antisocial behavior; genetic variation contributed to larger differences in antisocial behavior among abused children. The TPH1 and 5-HTTLPR polymorphisms also moderated the effects of maltreatment subtype on adult reports of antisocial behavior; again, the genetic effects were strongest for children who were abused. In addition, TPH1 moderated the effect of developmental timing of maltreatment and chronicity on adult reports of antisocial behavior. The findings elucidate how genetic

Full Text Available Introduction: The combined type of ADHD and alcohol dependence are two different disorders. Research demonstrate that 45-55% of patients diagnosed with ADHD also suffer from comorbid substance abuse, and 11-55% of patients diagnosed with substance abuse suffer from undiagnosed ADHD. Alcohol is by far the most widely used psychoactive substance in the European culture. The serotonintransporter (5HHT gene has been implicated as one of the candidate genes in both disorders in recent molecular genetic research. Aim: The aim of the present study was to seek a common clinical and biological marker for hyperkinetic disorder and youth drinking. Methods: The study was conducted between 2008 and 2012. The sample consisted of 100 combined type ADHD patients: 51 adolescents youth drinking and 100 individuals without mental disorders or addiction in a population-based group. The 5HHT gene polymorphism was examined using PCR (Polymerase Chain Reaction. Statistical analysis was conducted with STATISTICA.PL software (version 5.0.97 licensed by StatSoft, Inc. USA. Results: A preferential trend for the “s” short allele of the investigated 5HHT gene polymorphism was observed in all the groups of adolescents compared to the population-based group of adults without alcohol dependence (p=0.01. Conclusion: Based on the conducted study a provisional conclusion may be drawn that the presence of the short “s” allele of the 5HTT gene polymorphism may be a prognostic factor of impulsivity in ADHD and of predisposition to alcohol dependence.

Full Text Available Objectives: To examine the relationship between psychological and social factors (depression, emotional control, sexual abuse, and parental physical punishment and adolescent drive for Thinness and Bulimic behaviors in a large community sample, and to investigate possible genetic moderation.Method: Data were drawn from the Australian Temperament Project (ATP, a population-based cohort study that has followed a representative sample of 2443 participants from infancy to adulthood across 16 waves since 1983. A subsample of 650 participants (50.2% female of Caucasian descent who provided DNA were genotyped for a serotonintransporter promoter polymorphism (5-HTTLPR. Adolescent disordered eating attitudes and behaviors were assessed using the Bulimia and Drive for Thinness scales of the Eating Disorder Inventory-2 (15–16 years. Depression and emotional control were examined at the same age using the Short Mood and Feelings Questionnaire, and an ATP-devised measure of emotional control. History of sexual abuse and physical punishment were assessed retrospectively (23–24 years in a subsample of 467 of those providing DNA.Results: EDI-2 scores were associated with depression, emotional control, and retrospectively reported parental physical punishment. Although there was statistically significant moderation of the relationship between parental physical punishment and bulimic behaviors by 5-HTTLPR (p = 0.0048, genotypes in this subsample were not in Hardy–Weinberg Equilibrium. No other G×E interactions were significant. Conclusion: Findings from this study affirm the central importance of psychosocial processes in disordered eating patterns in adolescence. Evidence of moderation by 5-HTTLPR was not conclusive; however, genetic moderation observed in a subsample not in Hardy–Weinberg Equilibrium warrants further investigation.

4-[{sup 18}F]-ADAM is a potent serotonintransport imaging agent. We studied its toxicity in rats and radiation dosimetry in monkeys before human studies are undertaken. Single and multiple-dosage toxicity studies were conducted in Sprague-Dawley rats. Male and female rats were injected intravenously with 4-F-ADAM as a single dose of 1,023.7 {mu}g/kg (1,000 times the human dose) or as five consecutive daily doses of 102.37 {mu}g/kg (100 times the human dose). PET/CT scans were performed in seven Formosa Rock monkeys (four males and three females) using a Siemens Biograph scanner. After injection of 4-[{sup 18}F]-ADAM (182{+-}8 MBq), a low dose CT scan and a series of eight whole-body PET scans were performed. Whole-body images were acquired in 3-D mode. Time-activity data of source organs were used to calculate the residence times and estimate the absorbed radiation dose using OLINDA/EXM software. In the rats neither the single dose nor the five daily doses of 4-F-ADAM produced overt adverse effects clinically. In the monkeys the radiation doses received by most organs ranged between 7.1 and 35.7 {mu}Gy/MBq, and the urinary bladder was considered to be the critical organ. The effective doses extrapolated to male and female adult humans were 17.4 and 21.8 {mu}Sv/MBq, respectively. Toxicity studies in Sprague-Dawley rats and radiation dosimetry studies in Formosa Rock monkeys suggested that 4-[{sup 18}F]-ADAM is safe for use in human PET imaging studies. (orig.)

The human serotonintransporter (hSERT) has primary and allosteric binding sites for escitalopram and R-citalopram. Previous studies have established that the interaction of these two compounds at a low affinity allosteric binding site of hSERT can affect the dissociation of [(3)H]escitalopram from hSERT. The allosteric binding site involves a series of residues in the 10th, 11th, and 12th trans-membrane domains of hSERT. The low affinity allosteric activities of escitalopram and R-citalopram are essentially eliminated in a mutant hSERT with changes in some of these residues, namely A505V, L506F, I507L, S574T, I575T, as measured in dissociation binding studies. We confirm that in association binding experiments, R-citalopram at clinically relevant concentrations reduces the association rate of [(3)H]escitalopram as a ligand to wild type hSERT. We demonstrate that the ability of R-citalopram to reduce the association rate of escitalopram is also abolished in the mutant hSERT (A505V, L506F, I507L, S574T, I575T), along with the expected disruption the low affinity allosteric function on dissociation binding. This suggests that the allosteric binding site mediates both the low affinity and higher affinity interactions between R-citalopram, escitalopram, and hSERT. Our data add an additional structural basis for the different efficacies of escitalopram compared to racemic citalopram reported in animal studies and clinical trials, and substantiate the hypothesis that hSERT has complex allosteric mechanisms underlying the unexplained in vivo activities of its inhibitors.

Full Text Available In recent years, internet addiction disorder (IAD has become more prevalent worldwide and the recognition of its devastating impact on the users and society has rapidly increased. However, the neurobiological mechanism of IAD has not bee fully expressed. The present study was designed to determine if the striatal dopamine transporter (DAT levels measured by T99mc-TRODAT-1 single photon emission computed tomography (SPECT brain scans were altered in individuals with IAD. SPECT brain scans were acquired on 5 male IAD subjects and 9 healthy age-matched controls. The volume (V and weight (W of bilateral corpus striatum as well as the T99mc-TRODAT-1 uptake ratio of corpus striatum/the whole brain (Ra were calculated using mathematical models. It was displayed that DAT expression level of striatum was significantly decreased and the V, W, and Ra were greatly reduced in the individuals with IAD compared to controls. Taken together, these results suggest that IAD may cause serious damages to the brain and the neuroimaging findings further illustrate IAD is associated with dysfunctions in the dopaminergic brain systems. Our findings also support the claim that IAD may share similar neurobiological abnormalities with other addictive disorders.

Numerous studies link decreased serotonin metabolites with increased impulsive and aggressive traits. However, although pharmacological depletion of serotonin is associated with increased aggression, interventions aimed at directly decreasing serotonin neuron activity have supported the opposite association. Furthermore, it is not clear if altered serotonin activity during development may contribute to some of the observed associations. Here, we used two pharmacogenetic approaches in transgenic mice to selectively and reversibly reduce the firing of serotonin neurons in behaving animals. Conditional overexpression of the serotonin 1A receptor (Htr1a) in serotonin neurons showed that a chronic reduction in serotonin neuron firing was associated with heightened aggression. Overexpression of Htr1a in adulthood, but not during development, was sufficient to increase aggression. Rapid suppression of serotonin neuron firing by agonist treatment of mice expressing Htr1a exclusively in serotonin neurons also led to increased aggression. These data confirm a role of serotonin activity in setting thresholds for aggressive behavior and support a direct association between low levels of serotonin homeostasis and increased aggression.

Full Text Available The aim of this experiment was to demonstrate the ability of feeding serotonin (5-HT; 5-hydroxytryptamine precursors to increase 5-HT production during the transition from pregnancy to lactation and the effects this has on maternal energy metabolism in the liver and mammary gland. Pregnant rats (n = 45 were fed one of three diets: I control (CON, II CON supplemented with 0.2% 5-hydroxytryptophan (5-HTP or III CON supplemented with 1.35% L-tryptophan (L-TRP, beginning on d13 of pregnancy through d9 of lactation (d9. Serum (pre and post-partum, milk (daily, liver and mammary gland tissue (d9 were collected. Serum 5-HT was increased in the 5-HTP fed dams beginning on d20 of gestation and remained elevated through d9, while it was only increased on d9 in the L-TRP fed dams. 5-HT levels were increased in mammary gland and liver of both groups. Additionally, 5-HTP fed dams had serum and milk glucose levels similar to the CON, while L-TRP had decreased serum (d9 and milk glucose (all dates evaluated. Feeding 5-HTP resulted in increased mRNA expression of key gluconeogenic and glycolytic enzymes in liver and glucose transporters 1 and 8 (GLUT-1, -8 in the mammary gland. We demonstrated the location of GLUT-8 in the mammary gland both in the epithelial and vascular endothelial cells. Finally, phosphorylated 5' AMP-activated protein kinase (pAMPK, a known regulator of intracellular energy status, was elevated in mammary glands of 5-HTP fed dams. Our results suggest that increasing 5-HT production during the transition from pregnancy to lactation increases mRNA expression of enzymes involved in energy metabolism in the liver, and mRNA abundance and distribution of glucose transporters within the mammary gland. This suggests the possibility that 5-HT may be involved in regulating energy metabolism during the transition from pregnancy to lactation.

Full Text Available Abstract Background Serotonin is a neurotransmitter that has been linked to a wide variety of behaviors including feeding and body-weight regulation, social hierarchies, aggression and suicidality, obsessive compulsive disorder, alcoholism, anxiety, and affective disorders. Full understanding of serotonergic systems in the central nervous system involves genomics, neurochemistry, electrophysiology, and behavior. Though associations have been found between functions at these different levels, in most cases the causal mechanisms are unknown. The scientific issues are daunting but important for human health because of the use of selective serotonin reuptake inhibitors and other pharmacological agents to treat disorders in the serotonergic signaling system. Methods We construct a mathematical model of serotonin synthesis, release, and reuptake in a single serotonergic neuron terminal. The model includes the effects of autoreceptors, the transport of tryptophan into the terminal, and the metabolism of serotonin, as well as the dependence of release on the firing rate. The model is based on real physiology determined experimentally and is compared to experimental data. Results We compare the variations in serotonin and dopamine synthesis due to meals and find that dopamine synthesis is insensitive to the availability of tyrosine but serotonin synthesis is sensitive to the availability of tryptophan. We conduct in silico experiments on the clearance of extracellular serotonin, normally and in the presence of fluoxetine, and compare to experimental data. We study the effects of various polymorphisms in the genes for the serotonintransporter and for tryptophan hydroxylase on synthesis, release, and reuptake. We find that, because of the homeostatic feedback mechanisms of the autoreceptors, the polymorphisms have smaller effects than one expects. We compute the expected steady concentrations of serotonintransporter knockout mice and compare to

Full Text Available Several studies reported training-induced improvements in executive function tasks and also observed transfer to untrained tasks. However, the results are mixed and there is large interindividual variability within and across studies. Given that training-related performance changes would require modification, growth or differentiation at the cellular and synaptic level in the brain, research on critical moderators of brain plasticity potentially explaining such changes is needed. In the present study, a pre-post-follow-up design (N=122 and a three-weeks training of two response inhibition tasks (Go/NoGo and Stop-Signal was employed and genetic variation (Val66Met in the brain-derived neurotrophic factor (BDNF promoting differentiation and activity-dependent synaptic plasticity was examined. Because Serotonin (5-HT signaling and the interplay of BDNF and 5-HT are known to critically mediate brain plasticity, genetic variation in the 5-HT transporter (5-HTTLPR was also addressed. The overall results show that the kind of training (i.e., adaptive vs. non-adaptive did not evoke genotype-dependent differences. However, in the Go/NoGo task, better inhibition performance (lower commission errors were observed for BDNF Val/Val genotype carriers compared to Met-allele ones supporting similar findings from other cognitive tasks. Additionally, a gene-gene interaction suggests a more impulsive response pattern (faster responses accompanied by higher commission error rates in homozygous l-allele carriers relative to those with the s-allele of 5-HTTLPR. This, however, is true only in the presence of the Met-allele of BDNF, while the Val/Val genotype seems to compensate for such non-adaptive responding. Intriguingly, similar results were obtained for the Stop-Signal task. Here, differences emerged at post-testing, while no differences were observed at T1. In sum, although no genotype-dependent differences between the relevant training groups emerged suggesting

Introduction: [{sup 123}I]-2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine ([{sup 123}I]ADAM), a novel radiotracer, has promising application in the imaging of the serotonintransporter (SERT) in the human brain. In this study, the optimal scanning time for acquiring brain single photon emission computed tomography (SPECT) images was determined by performing dynamic SPECT studies at intervals from 0 to 6 h postinjection of [{sup 123}I]ADAM. Additionally, radiation-absorbed doses were determined for three healthy human subjects using attenuation-corrected images. Methods: Twelve subjects were randomized into one of three study groups as follows: whole-body distribution imaging (n=3), dynamic SPECT imaging (n=3) and brain SPECT imaging (n=6). The radiation-absorbed dose was calculated using MIRDOSE 3.0 software with attenuation-corrected data. The specific binding (SB) ratio of the brain stem was measured from dynamic SPECT images to determine the optimal scanning time. Results: Dynamic SPECT images showed that the SB of the brain stem gradually increased to a maximum 4 h postinjection. Single photon emission computed tomography images at 4 h postinjection showed a high uptake of the radiotracer (SB) in the hypothalamus (1.40{+-}0.12), brain stem (1.44{+-}0.16), pons (1.13{+-}0.14) and medial temporal lobe (0.59{+-}0.10). The mean adult male value of effective dose was 3.37x10{sup -2} mSv/MBq with a 4.8-h urine-voiding interval. Initial high uptake in SERT-rich sites was demonstrated in the lung and brain. A prominent washout of the radiotracer from the lung further increased brain radioactivity that reached a peak value of 5.03% of injected dose 40 min postinjection. Conclusions: [{sup 123}I]ADAM is a promising radiotracer for SPECT imaging of SERT in humans with acceptable dosimetry and high uptake in SERT-rich regions. Brain SPECT images taken within 4 h following injection show optimal levels of radiotracer uptake in known SERT sites. However, dynamic

Institutional care has been shown to lead to insecure and disorganized attachments and indiscriminate friendliness. Some children, however, are surprisingly resilient to the adverse environment. Here the protective role of the long variant of the serotonin receptor gene (5HTT) is explored in a small hypothesis-generating study of 37 Ukrainian…

Full Text Available Learning of associations between aversive stimuli and predictive cues is the basis of Pavlovian fear conditioning and is driven by a mismatch between expectation and outcome. To investigate whether serotonin modulates the formation of such aversive cue-outcome associations, we used functional magnetic resonance imaging (fMRI and dietary tryptophan depletion to reduce brain serotonin (5-HT levels in healthy human subjects. In a Pavlovian fear conditioning paradigm, 5-HT depleted subjects compared to a non-depleted control group exhibited attenuated autonomic responses to cues indicating the upcoming of an aversive event. These results were closely paralleled by reduced aversive learning signals in the amygdala and the orbitofrontal cortex, two prominent structures of the neural fear circuit. In agreement with current theories of serotonin as a motivational opponent system to dopamine in fear learning, our data provide first empirical evidence for a role of serotonin in representing formally derived learning signals for aversive events.

Learning of associations between aversive stimuli and predictive cues is the basis of Pavlovian fear conditioning and is driven by a mismatch between expectation and outcome. To investigate whether serotonin modulates the formation of such aversive cue-outcome associations, we used functional magnetic resonance imaging (fMRI) and dietary tryptophan depletion to reduce brain serotonin (5-HT) levels in healthy human subjects. In a Pavlovian fear conditioning paradigm, 5-HT depleted subjects compared to a non-depleted control group exhibited attenuated autonomic responses to cues indicating the upcoming of an aversive event. These results were closely paralleled by reduced aversive learning signals in the amygdala and the orbitofrontal cortex, two prominent structures of the neural fear circuit. In agreement with current theories of serotonin as a motivational opponent system to dopamine in fear learning, our data provide first empirical evidence for a role of serotonin in representing formally derived learning signals for aversive events.

Although both genetic factors and features of the social environment are important predictors of posttraumatic stress disorder (PTSD), there are few data examining gene-social environment interactions in studies of PTSD. The authors examined whether features of the social environment (county-level crime rate and unemployment) modified the association between the serotonin protein gene (SLC6A4) promoter variant (5-HTTLPR) and risk of current PTSD in a sample of 590 participants from the 2004 F...

The serotonintransporter radioligand [{sup 11}C]-3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile, or [{sup 11}C]DASB, was examined in order to assess its potential for measuring fluctuations in endogenous serotonin concentrations with positron emission tomography. Binding characteristics of [{sup 11}C]DASB and the propensity for serotonin to displace the tracer were explored in rat brain homogenates. Experiments showed that serotonin displaced [{sup 11}C]DASB in vitro. Ex vivo experiments performed after tranylcypromine injection (3 or 15 mg/kg) showed a dose-dependent trend in radioactivity uptake and suggested that serotonin may compete with [{sup 11}C]DASB for transporter binding.

In this review the authors summarize data of a potential role for serotonin in human skin physiology and pathology. The uncovering of endogenous serotonin synthesis and its transformation to melatonin underlines a putative important role of this pathway in melanocyte physiology and pathology. Pathways of the biosynthesis and biodegradation of serotonin have been characterized in human beings and its major cellular populations. Moreover, receptors of serotonin are expressed on keratinocytes, melanocytes, and fibroblasts and these mediate phenotypic actions on cellular proliferation and differentiation. And the widespread expression of a cutaneous seorotoninergic system indicates considerable selectivity of action to facilitate intra-, auto-, or paracrine mechanisms that define and influence skin function in a highly compartmentalized manner. Melatonin, in turn, can also act as a hormone, neurotransmitter, cytokine, biological modifier and immunomodulator. Thus, Serotonin local synthesis and cellular localization could thus become of great importance in the diagnosis and management of cutaneous pathology.

At Formerly Utilized Sites Remedial Action Program (FUSRAP) sites where the selected alternative for contaminated soil is excavation and off-site disposal, the most significant budget items of the remedial action are the costs for transportation and disposal of soil at an off-site facility. At these sites, the objective is to excavate and dispose of only those soils that exceed derived concentration guideline levels. In situ soil segregation using gross gamma detectors to guide the excavation is often challenging at sites where the soil contamination is overlain by clean soil or where the contaminated soil is located in isolated, subsurface pockets. In addition, data gaps are often identified during the alternative evaluation and selection process, resulting in increased uncertainty in the extent of subsurface contamination. In response, the U.S. Army Corps of Engineers, Buffalo District is implementing ex situ soil segregation methods. At the remediated Painesville Site, soils were excavated and fed through a conveyor-belt system, which automatically segregated them into above- and below-cleanup criteria discharge piles utilizing gamma spectroscopy. At the Linde Site and the Shallow Land Disposal Area (SLDA) Site, which are both in the remediation phase, soils are initially segregated during the excavation process using gross gamma detectors and then transported to a pad for confirmatory manual surveying and sampling. At the Linde Site, the ex situ soils are analyzed on the basis of a site-specific method, to establish compliance with beneficial reuse criteria that were developed for the Linde remediation. At the SLDA Site, the ex situ soils are surveyed and sampled based on Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM) final status survey guidance to demonstrate compliance with the derived concentration guideline levels. At all three sites, the ex situ soils that meet the site- specific DCGLs are retained on-site and used as backfill

Major airports have an average throughput of more than 100,000 passengers per day, some of which will need special assistance. The largest airports have a daily average throughput of more than 500 passengers with reduced mobility. A significant number of people and busses are assigned to provide ...

to resilience of the profile. Particular emphasis is put on the diffusionless limit, where these equations reduce to a simple dynamical system depending only on one single forcing parameter. This model is studied numerically, stressing experimentally observable signatures, and some of the perils of dimension...

Full Text Available Caenorhabditis elegans is as an ideal model system for the study of mechanisms underlying learning and memory. In the present study, we employed C. elegans assay system of thermotaxis memory to investigate the possible role of serotonin neurotransmitter in memory control. Our data showed that both mutations of tph-1, bas-1, and cat-4 genes, required for serotonin synthesis, and mutations of mod-5 gene, encoding a serotonin reuptake transporter, resulted in deficits in thermotaxis memory behavior. Exogenous treatment with serotonin effectively recovered the deficits in thermotaxis memory of tph-1 and bas-1 mutants to the level of wild-type N2. Neuron-specific activity assay of TPH-1 suggests that serotonin might regulate the thermotaxis memory behavior by release from the ADF sensory neurons. Ablation of ADF sensory neurons by expressing a cell-death activator gene egl-1 decreased the thermotaxis memory, whereas activation of ADF neurons by expression of a constitutively active protein kinase C homologue (pkc-1(gf increased the thermotaxis memory and rescued the deficits in thermotaxis memory in tph-1 mutants. Moreover, serotonin released from the ADF sensory neurons might act through the G-protein-coupled serotonin receptors of SER-4 and SER-7 to regulate the thermotaxis memory behavior. Genetic analysis implies that serotonin might further target the insulin signaling pathway to regulate the thermotaxis memory behavior. Thus, our results suggest the possible crucial role of serotonin and ADF sensory neurons in thermotaxis memory control in C. elegans.

Fast ion transport models presently implemented in the tokamak transport code TRANSP [R. J. Hawryluk, in Physics of Plasmas Close to Thermonuclear Conditions, CEC Brussels, 1 , 19 (1980)] are not capturing important aspects of the physics associated with resonant transport caused by instabilities such as Toroidal Alfv en Eigenmodes (TAEs). This work describes the implementation of a fast ion transport model consistent with the basic mechanisms of resonant mode-particle interaction. The model is formulated in terms of a probability distribution function for the particle's steps in phase space, which is consistent with the MonteCarlo approach used in TRANSP. The proposed model is based on the analysis of fast ion response to TAE modes through the ORBIT code [R. B. White et al., Phys. Fluids 27 , 2455 (1984)], but it can be generalized to higher frequency modes (e.g. Compressional and Global Alfv en Eigenmodes) and to other numerical codes or theories.

Serotonin is an ancient molecular signal and a recognized neurotransmitter brainwide distributed with particular presence in hippocampus. Almost all serotonin receptor subtypes are expressed in hippocampus, which implicates an intricate modulating system, considering that they can be localized as autosynaptic, presynaptic, and postsynaptic receptors, even colocalized within the same cell and being target of homo- and heterodimerization. Neurons and glia, including immune cells, integrate a functional network that uses several serotonin receptors to regulate their roles in this particular part of the limbic system.

Full Text Available Serotonin is an ancient molecular signal and a recognized neurotransmitter brainwide distributed with particular presence in hippocampus. Almost all serotonin receptor subtypes are expressed in hippocampus, which implicates an intricate modulating system, considering that they can be localized as autosynaptic, presynaptic, and postsynaptic receptors, even colocalized within the same cell and being target of homo- and heterodimerization. Neurons and glia, including immune cells, integrate a functional network that uses several serotonin receptors to regulate their roles in this particular part of the limbic system.

Serotonin is an ancient molecular signal and a recognized neurotransmitter brainwide distributed with particular presence in hippocampus. Almost all serotonin receptor subtypes are expressed in hippocampus, which implicates an intricate modulating system, considering that they can be localized as autosynaptic, presynaptic, and postsynaptic receptors, even colocalized within the same cell and being target of homo- and heterodimerization. Neurons and glia, including immune cells, integrate a functional network that uses several serotonin receptors to regulate their roles in this particular part of the limbic system. PMID:22629209

A major issue of concern in today's world is urban transport energy dependence and energy supply security. In an energy inter-dependent world, energy over-dependence brings risks to urban transport systems. Many urban areas are over-dependent on finite petroleum resources for transport. New technology and the development and integration of renewable resources into transport energy systems may reduce some of the current transport energy dependence of urban areas. However, the most effective means of reducing energy dependence is to first design urban areas for this condition. An urban policy framework is proposed that requires transport energy dependence to be measured and controlled in the urban development process. A new tool has been created for this purpose, the Transport Energy Specification (TES), which measures transport energy dependence of urban areas. This creates the possibility for cities to regulate urban development with respect to energy dependence. Trial assessments were performed in Germany, New Zealand and Brazil; initial analysis by transport and government professionals shows promise of this tool being included into urban policy. The TES combined with a regulatory framework has the potential to significantly reducetransport energy consumption and dependence in urban areas in the future. (auth)

As the airport traffic increases there is a continuous increase of passengers with different motor disabilities. Disabled passenger's assistance causes a biomechanical overload in airport workers. Some disabled passengers are classified by IATA as WCHC (wheel chair in cabin or Charlie). Our study, was performed in one of the most important Italian airport on Charlie passengers (about 10% of all assistances). We identified four critical points: 1) wheelchair and baggage moving (unstable load), 2) inclined ramps with worker's backwards steps and braked wheelchair to prevent passenger tipping or falling, 3) transfer from standard wheelchair to bicycle wheelchair, specifically designed for the aisle; 4.) transfer from bicycle wheelchair to aircraft seat. The last two points required sometimes to lift passengers over the armrest and positioning them on a window side seat, causing a serious increase of biomechanical load. For each critical point we have proposed technical and organizational measures to reduce airport worker's biomechanical risk.

Serotonin has an important role in vascular resistance and blood pressure control, and a functional serotonintransporter polymorphism has been associated with migraine. Disturbances in serotonin metabolism have been associated with autism, depression, and myoclonus related conditions, but serotonin has far more functions in the body. Familial hemiplegic migraine is a rare autosomal dominant subtype of migraine with aura in which attacks are associated with hemiparesis. We present two siblings with hemiplegic migraine, depression, progressive spastic paraparesis, myelopathy, and spinal cord atrophy. One of the sisters presented with prolonged coma after a migraine episode. Both sisters were found to have low cerebrospinal fluid serotonin metabolite (5-hydroxyindoleacetic acid), low platelet serotonin levels, and diminished serotonintransport capacity. Their clinical symptoms improved on 5-hydroxytryptophan replacement therapy. Mutational analysis of the CACNA1A and ATP1A2 genes was negative. This is the first time that systemic serotonin deficiency has been described in familial hemiplegic migraine. We hypothesize that the deficiency of serotonintransport may be part of a complex cellular membrane trafficking dysfunction involving not only the serotonintransporter but also other transporters and ion channels.

Serotonin is an ancient molecular signal and a recognized neurotransmitter brainwide distributed with particular presence in hippocampus. Almost all serotonin receptor subtypes are expressed in hippocampus, which implicates an intricate modulating system, considering that they can be localized as autosynaptic, presynaptic, and postsynaptic receptors, even colocalized within the same cell and being target of homo- and heterodimerization. Neurons and glia, including immune cells, integrate a fu...

Full Text Available The short allelic variant of the serotonintransporter (5-HTT promoter-linked polymorphic region (5-HTTLPR has been associated with the etiology of major depression by interaction with early life stress (ELS. A frequently observed endophenotype in depression is the abnormal regulation of levels of stress hormones such as glucocorticoids. It is hypothesized that altered central glucocorticoid influence on stress-related behavior and memory processes could underlie the depressogenic interaction of 5-HTTLPR and ELS. One possible mechanism could be the altered expression of the genes encoding the glucocorticoid and mineralocorticoid receptor (GR, MR and their inhibitory regulator FK506-binding protein 51 (FKBP5 in stress-related forebrain areas. To test this notion, we exposed heterozygous (5-HTT+/- and homozygous (5-HTT-/- serotonintransporter knockout rats and their wildtype littermates (5-HTT+/+ to daily 3 h maternal separations from postnatal day 2 to 14. In the medial prefrontal cortex (mPFC and hippocampus of the adult male offspring, we found that GR, MR and FKBP5 mRNA levels were affected by ELS x 5-HTT genotype interaction. Specifically, 5-HTT+/+ rats exposed to ELS showed decreased GR and FKBP5 mRNA in the dorsal and ventral mPFC, respectively. In contrast, 5-HTT+/- rats showed increased MR mRNA levels in the hippocampus and 5-HTT-/- rats showed increased FKBP5 mRNA in the ventral mPFC after ELS exposure. These findings indicate that 5-HTT genotype determines the specific adaptation of GR, MR and FKBP5 expression in response to early life adversity. Therefore, altered extra-hypothalamic glucocorticoid signaling should be considered to play a role in the depressogenic interaction of ELS and 5-HTTLPR.

Serotonin and insulin are key regulators of homeostatic mechanisms in the hypothalamus. However, in type 2 diabetes, the hypothalamic responsiveness to serotonin is not clearly established. We used a diabetic model, the Goto Kakizaki (GK) rats, to explore insulin receptor expression, insulin and serotonin efficiency in the hypothalamus and liver by means of Akt phosphorylation. Insulin or dexfenfluramine (stimulator of serotonin) treatment induced Akt phosphorylation in Wistar rats but not in GK rats that exhibit down-regulated insulin receptor. Studies in a neuroblastoma cell line showed that serotonin-induced Akt phosphorylation is PI3-kinase dependent. Finally, in response to food intake, hypothalamic serotonin release was reduced in GK rats, indicating impaired responsiveness of this neurotransmitter. In conclusion, hypothalamic serotonin as insulin efficiency is impaired in diabetic GK rats. The insulin-serotonin cross-talk and impairment observed is one potential key modification in the brain during the onset of diabetes.

Flavanoids and related polyphenols, among them hesperitin, have been shown to modulate cellular glucose transport by targeting SGLT-1 and GLUT-2 transport proteins. We aimed to investigate whether homoeriodictyol, which is structurally related to hesperitin, affects glucose uptake in differentiated Caco-2 cells as a model for the intestinal barrier. The results revealed that, in contrast to other polyphenols, the flavanon homoeriodictyol promotes glucose uptake by 29.0 ± 3.83% at a concentration of 100 μM. The glucose uptake stimulating effect was sensitive to phloridzin, but not to phloretin, indicating an involvement of the sodium-coupled glucose transporter SGLT-1, but not of sodium-independent glucose transporters (GLUT). In addition, in contrast to the increased extracellular serotonin levels by stimulation with 500 mM D-(+)-glucose, treatment with 100 μM homoeriodictyol decreased serotonin release by –48.8 ± 7.57% in Caco-2 cells via a phloridzin-sensitive signaling pathway. Extracellular serotonin levels were also reduced by –57.1 ± 5.43% after application of 0.01 μM homoeriodictyol to human neural SH-SY5Y cells. In conclusion, we demonstrate that homoeriodictyol affects both the glucose metabolism and the serotonin system in Caco-2 cells via a SGLT-1-meditated pathway. Furthermore, the results presented here support the usage of Caco-2 cells as a model for peripheral serotonin release. Further investigations may address the value of homoeriodictyol in the treatment of anorexia and malnutrition through the targeting of SGLT-1. PMID:28192456

The neuromodulator serotonin is found throughout the auditory system from the cochlea to the cortex. Although effects of serotonin have been reported at the level of single neurons in many brainstem nuclei, how these effects correspond to more integrated measures of auditory processing has not been well-explored. In the present study, we aimed to characterize the effects of serotonin on far-field auditory brainstem responses (ABR) across a wide range of stimulus frequencies and intensities. Using a mouse model, we investigated the consequences of systemic serotonin depletion, as well as the selective stimulation and suppression of the 5-HT1 and 5-HT2 receptors, on ABR latency and amplitude. Stimuli included tone pips spanning four octaves presented over a forty dB range. Depletion of serotoninreduced the ABR latencies in Wave II and later waves, suggesting that serotonergic effects occur as early as the cochlear nucleus. Further, agonists and antagonists of specific serotonergic receptors had different profiles of effects on ABR latencies and amplitudes across waves and frequencies, suggestive of distinct effects of these agents on auditory processing. Finally, most serotonergic effects were more pronounced at lower ABR frequencies, suggesting larger or more directional modulation of low-frequency processing. This is the first study to describe the effects of serotonin on ABR responses across a wide range of stimulus frequencies and amplitudes, and it presents an important step in understanding how serotonergic modulation of auditory brainstem processing may contribute to modulation of auditory perception.

Full Text Available Diverse neuropsychiatric disorders present dysfunctional memory and no effective treatment exits for them; likely as result of the absence of neural markers associated to memory. Neurotransmitter systems and signaling pathways have been implicated in memory and dysfunctional memory; however, their role is poorly understood. Hence, neural markers and cerebral functions and dysfunctions are revised. To our knowledge no previous systematic works have been published addressing these issues. The interactions among behavioral tasks, control groups and molecular changes and/or pharmacological effects are mentioned. Neurotransmitter receptors and signaling pathways, during normal and abnormally functioning memory with an emphasis on the behavioral aspects of memory are revised. With focus on serotonin, since as it is a well characterized neurotransmitter, with multiple pharmacological tools, and well characterized downstream signaling in mammals’ species. 5-HT1A, 5-HT4, 5-HT5, 5-HT6 and 5-HT7 receptors as well as SERT (serotonintransporter seem to be useful neural markers and/or therapeutic targets. Certainly, if the mentioned evidence is replicated, then the translatability from preclinical and clinical studies to neural changes might be confirmed. Hypothesis and theories might provide appropriate limits and perspectives of evidence

Diverse neuropsychiatric disorders present dysfunctional memory and no effective treatment exits for them; likely as result of the absence of neural markers associated to memory. Neurotransmitter systems and signaling pathways have been implicated in memory and dysfunctional memory; however, their role is poorly understood. Hence, neural markers and cerebral functions and dysfunctions are revised. To our knowledge no previous systematic works have been published addressing these issues. The interactions among behavioral tasks, control groups and molecular changes and/or pharmacological effects are mentioned. Neurotransmitter receptors and signaling pathways, during normal and abnormally functioning memory with an emphasis on the behavioral aspects of memory are revised. With focus on serotonin, since as it is a well characterized neurotransmitter, with multiple pharmacological tools, and well characterized downstream signaling in mammals' species. 5-HT1A, 5-HT4, 5-HT5, 5-HT6, and 5-HT7 receptors as well as SERT (serotonintransporter) seem to be useful neural markers and/or therapeutic targets. Certainly, if the mentioned evidence is replicated, then the translatability from preclinical and clinical studies to neural changes might be confirmed. Hypothesis and theories might provide appropriate limits and perspectives of evidence.

Background Clear recognition of the damaging effects of poverty on early childhood development has fueled an interest in interventions aimed at mitigating these harmful consequences. Psychosocial interventions aimed at alleviating the negative impacts of poverty on children are frequently shown to be of benefit, but effect sizes are typically small to moderate. However, averaging outcomes over an entire sample, as is typically done, could underestimate efficacy because weaker effects on less susceptible individuals would dilute estimation of effects on those more disposed to respond. This study investigates whether a genetic polymorphism of the serotonintransporter gene moderates susceptibility to a psychosocial intervention. Methods and findings We reanalyzed data from a randomized controlled trial of a home-visiting program delivered by community health workers in a black, isiXhosa-speaking population in Khayelitsha, South Africa. The intervention, designed to enhance maternal-infant attachment, began in the third trimester and continued until 6 mo postpartum. Implemented between April 1999 and February 2003, the intervention comprised 16 home visits delivered to 220 mother–infant dyads by specially trained community health workers. A control group of 229 mother–infant dyads did not receive the intervention. Security of maternal-infant attachment was the main outcome measured at infant age 18 mo. Compared to controls, infants in the intervention group were significantly more likely to be securely attached to their primary caregiver (odds ratio [OR] = 1.7, p = 0.029, 95% CI [1.06, 2.76], d = 0.29). After the trial, 162 intervention and 172 control group children were reenrolled in a follow-up study at 13 y of age (December 2012–June 2014). At this time, DNA collected from 279 children (134 intervention and 145 control) was genotyped for a common serotonintransporter polymorphism. There were both genetic data and attachment security data for 220 children

As quantum dots (QDs) are widely used in biomedical applications, the number of studies focusing on their biological properties is increasing. While several studies have attempted to evaluate the toxicity of QDs towards neural cells, the in vivo toxic effects on the nervous system and the molecular mechanisms are unclear. The aim of the present study was to investigate the neurotoxic effects and the underlying mechanisms of water-soluble cadmium telluride (CdTe) QDs capped with 3-mercaptopropionic acid (MPA) in Caenorhabditis elegans (C. elegans). Our results showed that exposure to MPA-capped CdTe QDs induced behavioral defects, including alterations to body bending, head thrashing, pharyngeal pumping and defecation intervals, as well as impaired learning and memory behavior plasticity, based on chemotaxis or thermotaxis, in a dose-, time- and size-dependent manner. Further investigations suggested that MPA-capped CdTe QDs exposure inhibited the transporters and receptors of glutamate, serotonin and dopamine in C. elegans at the genetic level within 24 h, while opposite results were observed after 72 h. Additionally, excessive reactive oxygen species (ROS) generation was observed in the CdTe QD-treated worms, which confirmed the common nanotoxicity mechanism of oxidative stress damage, and might overcome the increased gene expression of neurotransmitter transporters and receptors in C. elegans induced by long-term QD exposure, resulting in more severe behavioral impairments.

Soret transport, which is mass transport driven by thermal gradients, can be important in practical flames as well as laboratory flames by influencing transport of low molecular weight species (e.g., monatomic and diatomic hydrogen). In addition, gas-phase Soret transport of high molecular weight fuel species that are present in practical liquid fuels (e.g., octane or methanol) can be significant in practical flames (Rosner et al., 2000; Dakhlia et al., 2002) and in high pressure droplet evaporation (Curtis and Farrell, 1992), and it has also been shown that Soret transport effects can be important in determining oxygen diffusion rates in certain classes of microgravity droplet combustion experiments (Aharon and Shaw, 1998). It is thus useful to obtain information on flames under conditions where Soret effects can be clearly observed. This research is concerned with investigating effects of Soret transport on combustion of liquid fuels, in particular liquid fuel droplets. Reduced-gravity is employed to provide an ideal (spherically-symmetrical) experimental model with which to investigate effects of Soret transport on combustion. The research will involve performing reduced-gravity experiments on combustion of liquid fuel droplets in environments where Soret effects significantly influence transport of fuel and oxygen to flame zones. Experiments will also be performed where Soret effects are not expected to be important. Droplets initially in the 0.5 to 1 mm size range will be burned. Data will be obtained on influences of Soret transport on combustion characteristics (e.g., droplet burning rates, droplet lifetimes, gas-phase extinction, and transient flame behaviors) under simplified geometrical conditions that are most amenable to theoretical modeling (i.e., spherical symmetry). The experiments will be compared with existing theoretical models as well as new models that will be developed. Normal gravity experiments will also be performed.

Serotonin (5-hydroxytryptamien, 5-HT) has been linked to emotional and motivational aspects of human behavior, including anxiety, depression, impulsivity, etc. Several clinically effective drugs exert effects via 5-HT systems. Growing evidence suggests that those effects play an important role in learning and memory. Whether the role of serotonin is related to memory and/or behavioral or emotional aspects remains an important question. A key question that remains is whether 5-HT markers (e.g., receptors) directly or indirectly participate and/or contribute to the physiological and pharmacological basis of memory and its pathogenesis. The major aim of this paper is to re-examine some recent advances regarding mammalian 5-HT receptors and transporter in light of their physiological, pathophysiological and therapeutic implications for memory. We particularly address evidence involving 5-HT systems in behavioral, pharmacological, molecular, genetic and imaging results and memory. Finally, this paper aims to summarize a portion of the evidence about serotonin, memory and emotion from animal and human studies and provide an overview of potential tools, markers and cellular and molecular candidate mechanisms. It should be noted that there are several subjects that this paper only briefly touches upon, presenting only what may be the most salient findings in the context of memory, emotion and serotonin.

Serotonin (5-HT) modulates both neural and immune responses in vertebrates, but its role in insect immunity remains uncertain. We report that hemocytes in the caterpillar, Pieris rapae are able to synthesize 5-HT following activation by lipopolysaccharide. The inhibition of a serotonin-generating enzyme with either pharmacological blockade or RNAi knock-down impaired hemocyte phagocytosis. Biochemical and functional experiments showed that naive hemocytes primarily express 5-HT1B and 5-HT2B receptors. The blockade of 5-HT1B significantly reduced phagocytic ability; however, the blockade of 5-HT2B increased hemocyte phagocytosis. The 5-HT1B-null Drosophila melanogaster mutants showed higher mortality than controls when infected with bacteria, due to their decreased phagocytotic ability. Flies expressing 5-HT1B or 5-HT2B RNAi in hemocytes also showed similar sensitivity to infection. Combined, these data demonstrate that 5-HT mediates hemocyte phagocytosis through 5-HT1B and 5-HT2B receptors and serotonergic signaling performs critical modulatory functions in immune systems of animals separated by 500 million years of evolution.

Decreased serotonin function has consistently been shown to be highly correlated with impulsive aggression across a number of different experimental paradigms. Such lowered serotonergic indices appear to correlate with the dimension of aggression dyscontrol and/or impulsivity rather than with psychiatric diagnostic categories per se. Implications…

A new particle-based reduced-complexity model to simulate sediment transport and channel morphology in steep streams in presented. The model CAST (Cellular Automaton Sediment Transport) contains phenomenological parameterizations, deterministic or stochastic, of sediment supply, bed load transport, and particle entrainment and deposition in a cellular-automaton space with uniform grain size. The model reproduces a realistic bed morphology and typical fluctuations in transport rates observed in steep channels. Particle hop distances, from entrainment to deposition, are well fitted by exponential distributions, in agreement with field data. The effect of stochasticity in both the entrainment and the input rate is shown. A stochastic parameterization of the entrainment is essential to create and maintain a realistic channel morphology, while the intermittent transport of grains in CAST shreds the input signal and its stochastic variability. A jamming routine has been added to CAST to simulate the grain-grain and grain-bed interactions that lead to particle jamming and step formation in a step-pool stream. The results show that jamming is effective in generating steps in unsteady conditions. Steps are created during high-flow periods and they survive during low flows only in sediment-starved conditions, in agreement with the jammed-state hypothesis of Church and Zimmermann (2007). Reduced-complexity models like CAST give new insights into the dynamics of complex phenomena such as sediment transport and bedform stability and are a useful complement to fully physically based models to test research hypotheses.

Olanzapine is widely used in treating multiple domains of schizophrenia symptoms but induces serious metabolic side-effects. Recent evidence has showed that co-treatment of betahistine (a histaminergic H1 receptor agonist and H3 receptor antagonist) is effective for preventing olanzapine-induced weight gain/obesity, however it is not clear whether this co-treatment affects on the primary therapeutic receptor binding sites of olanzapine such as serotonergic 5-HT2A receptors (5-HT2AR) and dopaminergic D2 receptors (D2R). Therefore, this study investigated the effects of this co-treatment on 5-HT2AR, 5-HT transporter (5-HTT) and D2R bindings in various brain regions involved in antipsychotic efficacy. Female Sprague Dawley rats were administered orally (t.i.d.) with either olanzapine (1mg/kg), betahistine (2.7 mg/kg), olanzapine plus betahistine (O+B), or vehicle (control) for 2 weeks. Quantitative autoradiography was used to detect the density of [(3)H]ketanserin, [(3)H]paroxetine and [(3)H]raclopride binding site to 5-HT2AR, 5-HTT and D2R. Compared to the controls, olanzapine significantly decreased [(3)H]ketanserin bindings to 5-HT2AR in the prefrontal cortex, cingulate cortex, and nucleus accumbens. Similar changes in 5-HT2AR bindings in these nuclei were also observed in the O+B co-treatment group. Olanzapine also significantly decreased [(3)H]paroxetine binding to 5-HTT in the ventral tegmental area and substantia nigra, however, both olanzapine only and O+B co-treatment did not affect [(3)H]raclopride binding to D2R. The results confirmed the important role of 5-HT2AR in the efficacy of olanzapine, which is not influenced by the O+B co-treatment. Therefore, betahistine co-treatment would be an effective combination therapy to reduce olanzapine-induced weight gain side-effects without affecting olanzapine's actions on 5-HT2AR transmissions.

Several studies reported training-induced improvements in executive function tasks and also observed transfer to untrained tasks. However, the results are mixed and there is a large interindividual variability within and across studies. Given that training-related performance changes would require modification, growth or differentiation at the cellular and synaptic level in the brain, research on critical moderators of brain plasticity potentially explaining such changes is needed. In the present study, a pre-post-follow-up design (N = 122) and a 3-weeks training of two response inhibition tasks (Go/NoGo and Stop-Signal) was employed and genetic variation (Val66Met) in the brain-derived neurotrophic factor (BDNF) promoting differentiation and activity-dependent synaptic plasticity was examined. Because Serotonin (5-HT) signaling and the interplay of BDNF and 5-HT are known to critically mediate brain plasticity, genetic variation in the 5-HTT gene-linked polymorphic region (5-HTTLPR) was also addressed. The overall results show that the kind of training (i.e., adaptive vs. non-adaptive) did not evoke genotype-dependent differences. However, in the Go/NoGo task, better inhibition performance (lower commission errors) were observed for BDNF Val/Val genotype carriers compared to Met-allele ones supporting similar findings from other cognitive tasks. Additionally, a gene-gene interaction suggests a more impulsive response pattern (faster responses accompanied by higher commission error rates) in homozygous l-allele carriers relative to those with the s-allele of 5-HTTLPR. This, however, is true only in the presence of the Met-allele of BDNF, while the Val/Val genotype seems to compensate for such non-adaptive responding. Intriguingly, similar results were obtained for the Stop-Signal task. Here, differences emerged at post-testing, while no differences were observed at T1. In sum, although no genotype-dependent differences between the relevant training groups emerged

Black pepper (Piper nigrum L.) lowers blood lipids in vivo and inhibits cholesterol uptake in vitro, and piperine may mediate these effects. To test this, the present study aimed to compare actions of black pepper extract and piperine on (1) cholesterol uptake and efflux in Caco-2 cells, (2) the membrane/cytosol distribution of cholesterol transport proteins in these cells, and (3) the physicochemical properties of cholesterol micelles. Piperine or black pepper extract (containing the same amount of piperine) dose-dependently reduced cholesterol uptake into Caco-2 cells in a similar manner. Both preparations reduced the membrane levels of NPC1L1 and SR-BI proteins but not their overall cellular expression. Micellar cholesterol solubility of lipid micelles was unaffected except by 1 mg/mL concentration of black pepper extract. These data suggest that piperine is the active compound in black pepper and reduces cholesterol uptake by internalizing the cholesterol transporter proteins.

Low efficacy of vegetative filter strips (VFS) in reducing soluble nutrients has been reported in research articles. Solubility of phosphorus and nitrogen compounds is largely affected by pH of soil. Changing soil pH may result in a decrease in soluble nutrient transportation through VFS. This study was conducted to evaluate the effect of pH levels of VFS soil on soluble nutrient transport reduction from manure-borne runoff. Soil (loamy sand texture; bulk density 1.3 g cm-3) was treated with calcium carbonate to change pH at different pH treatment levels (5.5-6.5, 6.5-7.5, and 7.5-8.5), soil was packed into galvanized metal boxes, and tall fescue grasses were established in the boxes to simulate VFS. Boxes were placed in an open environment, tilted to a 3.0% slope, and 44.0 L manure-amended water was applied through the VFS by a pump at a rate of 1.45 L min-1. Water samples were collected at the inlet and outlet as well as from the leachate. Samples were analysed for ortho-phosphorus, ammonium nitrogen, nitrate nitrogen, and potassium. Highest transport reductions in ortho-phosphorus (42.4%) and potassium (20.5%) were observed at pH range 7.5-8.5. Ammonium nitrogen transport reduction was the highest at pH level of 6.5-7.5 and was 26.1%. Surface transport reduction in nitrate nitrogen was 100%, but leachate had the highest concentration of nitrate nitrogen. Mass transport reduction also suggested that higher pH in the VFS soil are effective in reducing some soluble nutrients transport.

As the population and economy continue to grow globally, demand for energy will continue to grow. The transportation sector relies solely on petroleum for its energy supply. The United States and China are the top two oil-importing countries. A major issue both countries face and are addressing is energy insecurity as a result of the demand for liquid fuels. Improvements in the energy efficiency of vehicles and the substitution of petroleum fuels with alternative fuels can help contain growth in the demand for transportation oil. Although most alternative transportation fuels - when applied to advanced vehicle technologies - can substantially reduce greenhouse emissions, coal-based liquid fuels may increase greenhouse gas emissions by twice as much as gasoline. Such technologies as carbon capture and storage may need to be employed to manage the greenhouse gas emissions of coal-based fuels. At present, there is no ideal transportation fuel option to solve problems related to transportation energy and greenhouse gas emissions. To solve these problems, research and development efforts are needed for a variety of transportation fuel options and advanced vehicle technologies.

The transport sector is a large contributor of harmful gaseous and particulate emissions in many urban areas. Black carbon is a component of short-lived particulate matter emitted predominantly by freight, public transport, and heavy- duty trucks. Controlling the emissions of black carbon from the transport sector is important for mitigating its impacts on climate, ecosystems, and human health. However, reducing the emissions of black carbon from mobile sources may be a challenging task in many developing urban areas due to economic, social, and technical constrains. Several emissions control technologies offer a proven approach for reducing emissions of black carbon from diesel-powered mobile sources, but the accurate quantification of associated emissions benefits in developing urban areas is not well documented. We describe recent advances for the estimation of black carbon emissions from the transport sector in real world driving conditions and present examples of the potential benefits of implementing various emission control technologies in Mexico. The results can help in the identification of key factors that hinder the implementation of control emissions for reducing emissions of black carbon elsewhere.

PURPOSE: To investigate the association between the 5-HT-transporter-gene-linked promoter region (5-HTTLPR) polymorphism and 20-mg paroxetine-induced ejaculation delay in men with lifelong premature ejaculation (LPE). MATERIALS AND METHODS: This was a prospective study of 10 weeks of paroxetine trea

Full Text Available Abstract Poor-insight obsessive-compulsive disorder (PI-OCD is a severe form of OCD where the 'typically obsessive' features of intrusive, 'egodystonic' feelings and thoughts are absent. PI-OCD is difficult to treat, often requiring very high doses of serotonergic drugs as well as antipsychotic augmentation. When this occurs, unpleasant side effects as nausea are common, eventually further reducing compliance to medication and increasing the need for pharmacological alternatives. We present the case of a PI-OCD patient who developed severe nausea after response to off-label doses of the selective serotonin reuptake inhibitor (SSRI, fluoxetine. Drug choices are discussed, providing pharmacodynamic rationales and hypotheses along with reports of rating scale scores, administered within a follow-up period of 52 weeks. A slight reduction of fluoxetine dose, augmentation with mirtazapine and a switch from amisulpride to olanzapine led to resolution of nausea while preserving the anti-OCD therapeutic effect. Mirtazapine and olanzapine have already been suggested for OCD treatment, although a lack of evidence exists about their role in the course of PI-OCD. Both mirtazapine and olanzapine also act as 5-hydroxytryptamine receptor type 3 (5-HT3 blockers, making them preferred choices especially in cases of drug-induced nausea.

Objective: To study the differences of serotonintransporter (SERT)mRNA expression levels in peripheral leukocytes between acute phase of schizophrenia patients and healthy control. To study the gender differences in the SERT mRNA expression levels between two groups.Method: 44 patients with acute phase of schizophrenia were selected in our hospital from May 2013 to November 2013, and then 42 healthy cases with the same age and gender were selected as the control group. The diagnosis of schizophrenia was established according to the DSM-IV-TR criteria. The severity of schizophrenia was assessed by the positive and negative syndromes scales(PANSS).All subjects were interviewed using self-designed questionnaire on general information and tested by quantitative real-time PCR method in SERT mRNA levels.Result:SERT mRNA levels in leukocytes in acute phase of schizophrenia patients were significantly higher than that in control group,the difference was statistically significant (P0.05). Conclusion: The over expression of SERT mRNA levels may be one of the biomarkers of schizophrenia in acute phase.%目的：探讨急性期精神分裂症与正常人群比较，外周血粒细胞5-HT转运体（Serotonin Transporter， SERT）mRNA表达水平的差异及各组SERT mRNA表达水平的性别差异。方法：选取2013年5月-11月于本院就诊的精神分裂症急性期患者44例为患者组，另选取与患者组性别、年龄匹配的正常人群42例为对照组，收集人口学资料，以阳性和阴性症状量表（PANSS）评估患者的症状严重程度，采用RT-PCR方法测定受试者的SERTmRNA表达水平。结果：精神分裂症患者组外周血粒细胞SERT mRNA表达水平高于正常对照组，两组比较差异有统计学意义（P0.05）。结论：外周血粒细胞SERT mRNA表达水平增高可能是潜在的精神分裂症急性期生物学标记物之一。

The neurotransmitter serotonin is an evolutionary ancient molecule that has remarkable modulatory effects in almost all central nervous system integrative functions, such as mood, anxiety, stress, aggression, feeding, cognition and sexual behavior. After giving a short outline of the serotonergic system (anatomy, receptors, transporter) the author's contributions over the last 40 years in the role of serotonin in depression, aggression, anxiety, stress and sexual behavior is outlined. Each area delineates the work performed on animal model development, drug discovery and development. Most of the research work described has started from an industrial perspective, aimed at developing animals models for psychiatric diseases and leading to putative new innovative psychotropic drugs, like in the cases of the SSRI fluvoxamine, the serenic eltoprazine and the anxiolytic flesinoxan. Later this research work mainly focused on developing translational animal models for psychiatric diseases and implicating them in the search for mechanisms involved in normal and diseased brains and finding new concepts for appropriate drugs.

This fact sheet provides an overview of the U.S. Department of Energy's Clean Cities program, which builds partnerships to reduce petroleum use in transportation in communities across the country. The U.S. Department of Energy's Clean Cities initiative advances the nation's economic, environmental, and energy security by supporting local actions to reduce petroleum consumption in transportation. Clean Cities accomplishes this work through the activities of nearly 100 local coalitions. These coalitions provide resources and technical assistance in the deployment of alternative and renewable fuels, idle-reduction measures, fuel economy improvements, and new transportation technologies, as they emerge. Clean Cities overarching goal is to reduce U.S. petroleum use by 2.5 billion gallons per year by 2020. To achieve this goal, Clean Cities employs three strategies: (1) Replace petroleum with alternative and renewable fuels, including natural gas, propane, electricity, ethanol, biodiesel, and hydrogen; (2) Reduce petroleum consumption through smarter driving practices and fuel economy improvements; and (3) Eliminate petroleum use through idle reduction and other fuel-saving technologies and practices.

A hybrid reduced model for relativistic electron beam transport based on the angular moments of the relativistic kinetic equation with a special closure is presented. It takes into account collective effects with the self-generated electromagnetic fields as well as collisional effects with the slowing down of the relativistic electrons by plasmons, bound and free electrons and their angular scattering on both ions and electrons. This model allows for fast computations of relativistic electron beam transport while describing their energy distribution evolution. Despite the loss of information concerning the angular distribution of the electron beam, the model reproduces analytical estimates in the academic case of a monodirectional and monoenergetic electron beam propagating through a warm and dense plasma and hybrid particle-in-cell simulation results in a realistic laser-generated electron beam transport case.

Rice (Oryza sativa L.) feeds ∼3 billion people. Due to the wide occurrence of arsenic (As) pollution in paddy soils and its efficient plant uptake, As in rice grains presents health risks. Genetic manipulation may offer an effective approach to reduce As accumulation in rice grains. The genetics of As uptake and metabolism have been elucidated and target genes have been identified for genetic engineering to reduce As accumulation in grains. Key processes controlling As in grains include As uptake, arsenite (AsIII) efflux, arsenate (AsV) reduction and AsIII sequestration, and As methylation and volatilization. Recent advances, including characterization of AsV uptake transporter OsPT8, AsV reductase OsHAC1;1 and OsHAC1;2, rice glutaredoxins, and rice ABC transporter OsABCC1, make many possibilities to develop low-arsenic rice. PMID:28298917

Full Text Available With the purpose of establishing an effective subsidy scheme to reduce Greenhouse Gas (GHG emissions, this paper proposes a two-stage game for a competitive urban transport market. In the first stage, the authority determines operating subsidies based on social welfare maximization. Observing the predetermined subsidies, two transit operators set fares and frequencies to maximize their own profits at the second stage. The detailed analytical and numerical analyses demonstrate that of the three proposed subsidy schemes, the joint implementation of trip-based and frequency-related subsidies not only generates the largest welfare gains and makes competitive operators provide equilibrium fares and frequencies, which largely resemble first-best optimal levels but also greatly contributes to reducing Greenhouse Gas (GHG emissions on major urban transport corridors.

Serotonin signalling is considered critical for an appropriate and dynamic adaptation to stress. Previously, we have shown that prefrontal serotonintransporter (SERT) binding is positively associated with the cortisol awakening response (CAR) (Frokjaer et al., 2013), which is an index...... and serotonin signaling in vivo in humans. We suggest that higher synaptic serotonin concentration, here indexed by lower 5-HT4r binding, supports HPA-axis dynamics, which in healthy volunteers is reflected by a robust CAR....... of hypothalamic-pituitary-adrenal (HPA)-axis output dynamics. Here, we investigated in healthy individuals if cerebral serotonin 4 receptor (5-HT4r) binding, reported to be a proxy for serotonin levels, is associated with CAR. Thirty healthy volunteers (25 males, age range 20-56 years) underwent 5-HT4r PET...

Emergency department (ED) crowding is widespread, and can result in care delays, medical errors, increased costs, and decreased patient satisfaction. Simultaneously, while capacity constraints on EDs are worsening, contributing factors such as patient volume and inpatient bed capacity are often outside the influence of ED administrators. Therefore, systems engineering approaches that improve throughput and reduce waste may hold the most readily available gains. Decreasing radiology turnaround times improves ED patient throughput and decreases patient waiting time. We sought to investigate the impact of systems engineering science targeting ED radiology transport delays and determine the most effective techniques. This prospective, before-and-after analysis of radiology process flow improvements in an academic hospital ED was exempt from institutional review board review as a quality improvement initiative. We hypothesized that reorganization of radiology transport would improve radiology cycle time and reduce waste. The intervention included systems engineering science-based reorganization of ED radiology transport processes, largely using Lean methodologies, and adding no resources. The primary outcome was average transport time between study order and complete time. All patients presenting between 8/2013-3/2016 and requiring plain film imaging were included. We analyzed electronic medical record data using Microsoft Excel and SAS version 9.4, and we used a two-sample t-test to compare data from the pre- and p